diff --git a/gen/org/solovyev/android/calculator/R.java b/gen/org/solovyev/android/calculator/R.java
index be166f9d..37993712 100644
--- a/gen/org/solovyev/android/calculator/R.java
+++ b/gen/org/solovyev/android/calculator/R.java
@@ -26,69 +26,82 @@ containing a value of this type.
          */
         public static final int textUp=0x7f010000;
     }
+    public static final class color {
+        public static final int button_text=0x7f050001;
+        public static final int magic_flame=0x7f050000;
+    }
     public static final class drawable {
-        public static final int down=0x7f020000;
-        public static final int icon=0x7f020001;
-        public static final int not_ok=0x7f020002;
-        public static final int ok=0x7f020003;
-        public static final int up=0x7f020004;
+        public static final int blue_button=0x7f020000;
+        public static final int button=0x7f020001;
+        public static final int down=0x7f020002;
+        public static final int icon=0x7f020003;
+        public static final int not_ok=0x7f020004;
+        public static final int ok=0x7f020005;
+        public static final int up=0x7f020006;
     }
     public static final class id {
-        public static final int calibrationArrow=0x7f080000;
-        public static final int calibrationButton=0x7f080001;
-        public static final int calibrationStart=0x7f080002;
-        public static final int curlyBracketsButton=0x7f080016;
-        public static final int editText=0x7f080003;
-        public static final int eigthDigitButton=0x7f080012;
-        public static final int equalsButton=0x7f080014;
-        public static final int fiveDigitButton=0x7f08000c;
-        public static final int fourDigitButton=0x7f08000b;
-        public static final int historyButton=0x7f08001b;
-        public static final int menu_item_help=0x7f08001e;
-        public static final int menu_item_settings=0x7f08001d;
-        public static final int minusButton=0x7f08000f;
-        public static final int muliplicationButton=0x7f080008;
-        public static final int nineDigitButton=0x7f080013;
-        public static final int numericButton=0x7f080019;
-        public static final int oneDigitButton=0x7f080005;
-        public static final int piButton=0x7f08001c;
-        public static final int plusButton=0x7f080009;
-        public static final int pointDigitButton=0x7f080018;
-        public static final int resultEditText=0x7f080004;
-        public static final int roundBracketsButton=0x7f08000a;
-        public static final int sevenDigitButton=0x7f080011;
-        public static final int simplifyButton=0x7f08001a;
-        public static final int sixDigitButton=0x7f08000d;
-        public static final int sqrtButton=0x7f080015;
-        public static final int squareBracketsButton=0x7f080010;
-        public static final int subtractionButton=0x7f08000e;
-        public static final int threeDigitButton=0x7f080007;
-        public static final int twoDigitButton=0x7f080006;
-        public static final int zeroDigitButton=0x7f080017;
+        public static final int calibrationArrowLeft=0x7f090001;
+        public static final int calibrationArrowRight=0x7f090004;
+        public static final int calibrationButtonLeft=0x7f090002;
+        public static final int calibrationButtonRight=0x7f090003;
+        public static final int calibrationStart=0x7f090005;
+        public static final int curlyBracketsButton=0x7f09001b;
+        public static final int divisionButton=0x7f090011;
+        public static final int editText=0x7f090006;
+        public static final int eigthDigitButton=0x7f090014;
+        public static final int equalsButton=0x7f090016;
+        public static final int fiveDigitButton=0x7f09000f;
+        public static final int fourDigitButton=0x7f09000e;
+        public static final int historyButton=0x7f090020;
+        public static final int menu_item_help=0x7f090022;
+        public static final int menu_item_settings=0x7f090021;
+        public static final int muliplicationButton=0x7f09000c;
+        public static final int nineDigitButton=0x7f090015;
+        public static final int numericButton=0x7f09001e;
+        public static final int oneDigitButton=0x7f090009;
+        public static final int panelswitch=0x7f090008;
+        public static final int piButton=0x7f09001c;
+        public static final int plusButton=0x7f09000d;
+        public static final int pointDigitButton=0x7f09001d;
+        public static final int resultEditText=0x7f090007;
+        public static final int roundBracketsButton=0x7f090019;
+        public static final int sevenDigitButton=0x7f090013;
+        public static final int simplePad=0x7f090000;
+        public static final int simplifyButton=0x7f09001f;
+        public static final int sixDigitButton=0x7f090010;
+        public static final int sqrtButton=0x7f090017;
+        public static final int squareBracketsButton=0x7f09001a;
+        public static final int subtractionButton=0x7f090012;
+        public static final int threeDigitButton=0x7f09000b;
+        public static final int twoDigitButton=0x7f09000a;
+        public static final int zeroDigitButton=0x7f090018;
     }
     public static final class layout {
         public static final int drag_button_calibration=0x7f030000;
         public static final int main=0x7f030001;
     }
     public static final class menu {
-        public static final int main_menu=0x7f070000;
+        public static final int main_menu=0x7f080000;
     }
     public static final class string {
-        public static final int c_app_name=0x7f050000;
-        public static final int c_app_settings=0x7f050001;
-        public static final int c_down=0x7f050008;
-        public static final int c_help=0x7f050004;
-        public static final int c_prefs_drag_button_calibration=0x7f050006;
-        public static final int c_prefs_drag_button_calibration_summary=0x7f050007;
-        public static final int c_prefs_main_category=0x7f050005;
-        public static final int c_restart=0x7f05000a;
-        public static final int c_settings=0x7f050003;
-        public static final int c_up=0x7f050009;
-        public static final int syntax_error=0x7f050002;
+        public static final int c_app_name=0x7f060000;
+        public static final int c_app_settings=0x7f060001;
+        public static final int c_down=0x7f060008;
+        public static final int c_help=0x7f060004;
+        public static final int c_prefs_drag_button_calibration=0x7f060006;
+        public static final int c_prefs_drag_button_calibration_summary=0x7f060007;
+        public static final int c_prefs_main_category=0x7f060005;
+        public static final int c_restart=0x7f06000a;
+        public static final int c_settings=0x7f060003;
+        public static final int c_up=0x7f060009;
+        public static final int syntax_error=0x7f060002;
     }
     public static final class style {
-        public static final int digitButtonStyle=0x7f060001;
-        public static final int editTextInputStyle=0x7f060000;
+        public static final int button_small_style=0x7f070003;
+        public static final int button_style=0x7f070001;
+        public static final int digitButtonStyle=0x7f070002;
+        public static final int display_style=0x7f070004;
+        public static final int editTextInputStyle=0x7f070000;
     }
     public static final class xml {
         public static final int preferences=0x7f040000;
diff --git a/res/drawable/blue_button.xml b/res/drawable/blue_button.xml
new file mode 100644
index 00000000..f4d6059b
--- /dev/null
+++ b/res/drawable/blue_button.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2007 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <gradient android:startColor="#071622" android:endColor="#253541"
+            android:angle="90"/>
+    <corners android:radius="0dp" />
+</shape>
diff --git a/res/drawable/button.xml b/res/drawable/button.xml
new file mode 100644
index 00000000..e5112ee1
--- /dev/null
+++ b/res/drawable/button.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2007 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <gradient android:startColor="#000000" android:endColor="#333333"
+            android:angle="90"/>
+    <corners android:radius="0dp" />
+</shape>
diff --git a/res/layout/drag_button_calibration.xml b/res/layout/drag_button_calibration.xml
index 93fbaef5..b01fdbc9 100644
--- a/res/layout/drag_button_calibration.xml
+++ b/res/layout/drag_button_calibration.xml
@@ -2,29 +2,46 @@
 
 <LinearLayout xmlns:a="http://schemas.android.com/apk/res/android"
 			  xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
-
 			  a:orientation="vertical"
-			  a:padding="6dp"
-			  a:layout_width="fill_parent"
-			  a:layout_height="fill_parent">
+			  a:layout_width="match_parent"
+			  a:layout_height="match_parent"
+			  a:background="#ff000000">
 
-	<LinearLayout 	a:orientation="horizontal"
-					a:layout_width="fill_parent"
-					a:layout_height="wrap_content">
+	<LinearLayout
+			a:id="@+id/simplePad"
+			a:layout_width="match_parent"
+			a:layout_height="match_parent"
+			a:orientation="vertical"
+			a:layout_gravity="center">
 
-		<ImageView a:id="@+id/calibrationArrow"
-				   a:layout_gravity="left"
-				   a:layout_width="80dp"
-				   a:layout_height="80dp"/>
+		<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
 
-		<org.solovyev.android.view.DirectionDragButton a:id="@+id/calibrationButton"
-											  a:text=""
-											  calc:textUp="@string/c_up"
-											  calc:textDown="@string/c_down"
-											  style="@style/digitButtonStyle"
-											  a:layout_width="80dp"
-											  a:layout_height="80dp"
-											  a:layout_gravity="center_horizontal"/>
+			<ImageView a:id="@+id/calibrationArrowLeft"
+					   a:layout_gravity="left"
+					   a:layout_width="80dp"
+					   a:layout_height="80dp"/>
+
+			<org.solovyev.android.view.DirectionDragButton a:id="@+id/calibrationButtonLeft"
+														   a:text=""
+														   calc:textUp="@string/c_up"
+														   calc:textDown="@string/c_down"
+														   a:layout_width="80dp"
+														   a:layout_height="80dp"
+														   style="@style/digitButtonStyle"/>
+
+			<org.solovyev.android.view.DirectionDragButton a:id="@+id/calibrationButtonRight"
+														   a:text=""
+														   calc:textUp="@string/c_up"
+														   calc:textDown="@string/c_down"
+														   a:layout_width="80dp"
+														   a:layout_height="80dp"
+														   style="@style/digitButtonStyle"/>
+
+			<ImageView a:id="@+id/calibrationArrowRight"
+					   a:layout_gravity="right"
+					   a:layout_width="80dp"
+					   a:layout_height="80dp"/>
+		</LinearLayout>
 	</LinearLayout>
 
 	<Button a:id="@+id/calibrationStart"
diff --git a/res/layout/main.xml b/res/layout/main.xml
index 5047a00c..dd3a7bd7 100644
--- a/res/layout/main.xml
+++ b/res/layout/main.xml
@@ -1,65 +1,166 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout 
-	xmlns:a="http://schemas.android.com/apk/res/android"
-	xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
-	
-    a:orientation="vertical"
-    a:layout_width="fill_parent"
-    a:layout_height="fill_parent">
-    
-    <EditText 
-    		a:id="@+id/editText"
-    		style="@style/editTextInputStyle" 
-    		a:maxLines="5"
-    		a:minLines="5"
-    		a:gravity="top|left"
-        	a:textAppearance="?android:attr/textAppearanceMedium"
-        	a:typeface="monospace"
-    		a:singleLine="false" />
-    		
-	<EditText 
-    		a:id="@+id/resultEditText"
-    		style="@style/editTextInputStyle" 
-    		a:gravity="top|left"
-        	a:textAppearance="?android:attr/textAppearanceMedium"
-        	a:typeface="monospace"
-        	a:editable="false"
-        	a:focusable="false"/>
-    		
-    <TableLayout 
-    	a:layout_width="fill_parent"
-    	a:layout_height="fill_parent">
-    	<TableRow>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/oneDigitButton" a:text="1" calc:textUp="sin" calc:textDown="asin" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/twoDigitButton" a:text="2" calc:textUp="cos" calc:textDown="acos"  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/threeDigitButton" a:text="3" calc:textUp="tg" calc:textDown="atg"  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-			<org.solovyev.android.view.DirectionDragButton a:id="@+id/muliplicationButton" a:text="*" calc:textUp="^" calc:textDown="^2" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-   			<org.solovyev.android.view.DirectionDragButton a:id="@+id/plusButton" a:text="+" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-   			<org.solovyev.android.view.DirectionDragButton a:id="@+id/roundBracketsButton" a:text="()" calc:textUp="(" calc:textDown=")" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	</TableRow>
-    	<TableRow>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/fourDigitButton" a:text="4" calc:textUp="exp" calc:textDown="mod"  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/fiveDigitButton" a:text="5" calc:textUp="log" calc:textDown="ln"  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/sixDigitButton" a:text="6" calc:textUp="!" calc:textDown=""  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/subtractionButton" a:text="/" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-   			<org.solovyev.android.view.DirectionDragButton a:id="@+id/minusButton" a:text="-" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/squareBracketsButton" a:text="[]" calc:textUp="[" calc:textDown="]" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	</TableRow>
-    	<TableRow>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/sevenDigitButton" a:text="7" calc:textUp="" calc:textDown=""  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/eigthDigitButton" a:text="8" calc:textUp="" calc:textDown=""  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/nineDigitButton" a:text="9" calc:textUp="" calc:textDown=""  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/equalsButton" a:text="=" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/sqrtButton" a:text="sqrt" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/curlyBracketsButton" a:text="{}" calc:textUp="{" calc:textDown="}" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	</TableRow>
-    	<TableRow>
-    		<org.solovyev.android.view.DirectionDragButton a:id="@+id/zeroDigitButton" a:text="0" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/pointDigitButton" a:text="." calc:textDown=","  style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/numericButton" a:text="numeric" style="@style/digitButtonStyle" a:onClick="numericButtonClickHandler"/>
-    	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/simplifyButton" a:text="simplify" style="@style/digitButtonStyle" a:onClick="simplifyButtonClickHandler"/>
-       	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/historyButton" calc:textUp="undo" calc:textDown="redo" style="@style/digitButtonStyle"/>
-       	    <org.solovyev.android.view.DirectionDragButton a:id="@+id/piButton" a:text="pi" calc:textUp="e" style="@style/digitButtonStyle" a:onClick="digitButtonClickHandler"/>
-    	</TableRow>
-    </TableLayout>
+
+<LinearLayout xmlns:a="http://schemas.android.com/apk/res/android"
+			  xmlns:calc="http://schemas.android.com/apk/res/org.solovyev.android.calculator"
+			  a:orientation="vertical"
+			  a:layout_width="match_parent"
+			  a:layout_height="match_parent"
+			  a:background="#ff000000">
+
+	<LinearLayout
+			a:orientation="vertical"
+			a:layout_width="match_parent"
+			a:layout_height="100dp"
+			a:layout_weight="2">
+
+		<EditText
+				a:id="@+id/editText"
+				style="@style/editTextInputStyle"
+				a:maxLines="5"
+				a:minLines="5"
+				a:gravity="top|left"
+				a:textAppearance="?android:attr/textAppearanceMedium"
+				a:typeface="monospace"
+				a:singleLine="false"/>
+
+		<EditText
+				a:id="@+id/resultEditText"
+				style="@style/editTextInputStyle"
+				a:gravity="top|left"
+				a:textAppearance="?android:attr/textAppearanceMedium"
+				a:minLines="1"
+				a:height="10dp"
+				a:typeface="monospace"
+				a:editable="false"
+				a:focusable="false"/>
+	</LinearLayout>
+
+
+	<org.solovyev.android.view.PanelSwitcher
+			a:id="@+id/panelswitch"
+			a:layout_width="match_parent"
+			a:layout_height="0dp"
+			a:layout_weight="5">
+
+		<LinearLayout
+				a:id="@+id/simplePad"
+				a:layout_width="match_parent"
+				a:layout_height="match_parent"
+				a:orientation="vertical"
+				a:layout_gravity="center">
+
+			<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/oneDigitButton" a:text="1" calc:textUp="sin"
+															   calc:textDown="asin" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/twoDigitButton" a:text="2" calc:textUp="cos"
+															   calc:textDown="acos" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/threeDigitButton" a:text="3" calc:textUp="tg"
+															   calc:textDown="atg" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/muliplicationButton" a:text="*"
+															   calc:textUp="^"
+															   calc:textDown="^2" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/plusButton" a:text="+"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+			</LinearLayout>
+
+			<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/fourDigitButton" a:text="4" calc:textUp="exp"
+															   calc:textDown="mod" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/fiveDigitButton" a:text="5" calc:textUp="log"
+															   calc:textDown="ln" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/sixDigitButton" a:text="6" calc:textUp="!"
+															   calc:textDown="" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/divisionButton" a:text="/"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/subtractionButton" a:text="-"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+			</LinearLayout>
+
+			<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/sevenDigitButton" a:text="7" calc:textUp=""
+															   calc:textDown="" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/eigthDigitButton" a:text="8" calc:textUp=""
+															   calc:textDown="" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/nineDigitButton" a:text="9" calc:textUp=""
+															   calc:textDown="" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/equalsButton" a:text="="
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/sqrtButton" a:text="sqrt"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+			</LinearLayout>
+
+			<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/zeroDigitButton" a:text="0"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/roundBracketsButton" a:text="()"
+															   calc:textUp="("
+															   calc:textDown=")" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/squareBracketsButton" a:text="[]"
+															   calc:textUp="["
+															   calc:textDown="]" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/curlyBracketsButton" a:text="{}"
+															   calc:textUp="{"
+															   calc:textDown="}" style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/piButton" a:text="pi" calc:textUp="e"
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+			</LinearLayout>
+
+
+			<LinearLayout a:layout_weight="1" a:layout_width="match_parent" a:layout_height="0dp">
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/pointDigitButton" a:text="." calc:textDown=","
+															   style="@style/digitButtonStyle"
+															   a:onClick="digitButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/numericButton" a:text="numeric"
+															   style="@style/digitButtonStyle"
+															   a:onClick="numericButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/simplifyButton" a:text="simplify"
+															   style="@style/digitButtonStyle"
+															   a:onClick="simplifyButtonClickHandler"/>
+
+				<org.solovyev.android.view.DirectionDragButton a:id="@+id/historyButton" calc:textUp="undo"
+															   calc:textDown="redo" style="@style/digitButtonStyle"/>
+
+			</LinearLayout>
+		</LinearLayout>
+	</org.solovyev.android.view.PanelSwitcher>
 </LinearLayout>
diff --git a/res/values/colors.xml b/res/values/colors.xml
new file mode 100644
index 00000000..56cc6b39
--- /dev/null
+++ b/res/values/colors.xml
@@ -0,0 +1,4 @@
+<resources>
+    <color name="magic_flame">#00ffffff</color>
+    <color name="button_text">#ffffffff</color>
+</resources>
\ No newline at end of file
diff --git a/res/values/styles.xml b/res/values/styles.xml
index aec8278e..be73b39e 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -6,10 +6,34 @@
         <item name="android:layout_height">wrap_content</item>
         <item name="android:typeface">monospace</item>
     </style>
-    
-   <style name="digitButtonStyle">
-        <item name="android:width">50dp</item>
-        <item name="android:height">50dp</item>
-        <item name="android:typeface">monospace</item>
-    </style> 
-</resources>
\ No newline at end of file
+
+    <style name="button_style">
+        <item name="android:layout_width">match_parent</item>
+        <item name="android:layout_height">match_parent</item>
+        <item name="android:layout_weight">1</item>
+        <item name="android:focusable">true</item>
+        <item name="android:background">@drawable/button</item>
+        <item name="android:layout_marginLeft">1dp</item>
+    </style>
+
+    <style name="digitButtonStyle" parent="button_style">
+        <item name="android:background">@drawable/blue_button</item>
+    </style>
+
+    <style name="button_small_style" parent="button_style">
+        <item name="android:textSize">30dp</item>
+    </style>
+
+    <style name="display_style">
+        <item name="android:textSize">40dp</item>
+        <item name="android:gravity">right|center_vertical</item>
+        <item name="android:textColor">#ffffff</item>
+        <item name="android:maxLines">1</item>
+        <item name="android:scrollbars">none</item>
+        <item name="android:scrollHorizontally">true</item>
+        <item name="android:layout_width">match_parent</item>
+        <item name="android:layout_height">match_parent</item>
+        <item name="android:padding">8dp</item>
+    </style>
+
+</resources>
diff --git a/src/org/solovyev/android/calculator/CalculatorActivity.java b/src/org/solovyev/android/calculator/CalculatorActivity.java
index 0d1263d0..d778e0ab 100644
--- a/src/org/solovyev/android/calculator/CalculatorActivity.java
+++ b/src/org/solovyev/android/calculator/CalculatorActivity.java
@@ -10,7 +10,9 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.os.Handler;
+import android.util.TypedValue;
 import android.view.*;
+import android.widget.TextView;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.view.*;
@@ -26,7 +28,9 @@ import android.util.Log;
 import android.widget.EditText;
 import org.solovyev.util.math.Point2d;
 
-public class CalculatorActivity extends Activity {
+public class CalculatorActivity extends Activity implements FontSizeAdjuster{
+
+    private static final int HVGA_WIDTH_PIXELS  = 320;
 
 	@NotNull
 	private EditText editText;
@@ -273,4 +277,18 @@ public class CalculatorActivity extends Activity {
 	private void showHelp() {
 		Log.d(CalculatorActivity.class + "showHelp()", "Show help!");
 	}
+
+        /**
+     * The font sizes in the layout files are specified for a HVGA display.
+     * Adjust the font sizes accordingly if we are running on a different
+     * display.
+     */
+	@Override
+    public void adjustFontSize(@NotNull TextView view) {
+        float fontPixelSize = view.getTextSize();
+        Display display = getWindowManager().getDefaultDisplay();
+        int h = Math.min(display.getWidth(), display.getHeight());
+        float ratio = (float)h/HVGA_WIDTH_PIXELS;
+        view.setTextSize(TypedValue.COMPLEX_UNIT_PX, fontPixelSize*ratio);
+    }
 }
\ No newline at end of file
diff --git a/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java b/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java
index cd934173..a2efa2b2 100644
--- a/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java
+++ b/src/org/solovyev/android/calculator/DragButtonCalibrationActivity.java
@@ -1,7 +1,6 @@
 package org.solovyev.android.calculator;
 
 import android.app.Activity;
-import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
@@ -24,7 +23,6 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.prefs.Preferences;
 
 /**
  * User: serso
@@ -33,14 +31,10 @@ import java.util.prefs.Preferences;
  */
 public class DragButtonCalibrationActivity extends Activity {
 
-	@NotNull
-	private DragDirection dragDirection = DragDirection.up;
-
 	@NotNull
 	private final List<DragData> dragHistory = new ArrayList<DragData>();
 
-	@NotNull
-	private ImageView calibrationArrow;
+	private final Map<DragButton, CalibrationArrow> map = new HashMap<DragButton, CalibrationArrow>();
 
 	public static final String PREFERENCES = "dragButtonPreferences";
 
@@ -52,7 +46,6 @@ public class DragButtonCalibrationActivity extends Activity {
 	private static final float DEFAULT_VALUE = -999;
 	private static final int MIN_HISTORY_FOR_CALIBRATION = 10;
 	public static final String INTENT_ACTION = "org.solovyev.android.calculator.DragButtonPreferencesChanged";
-	;
 
 	public static enum PreferenceType {
 		angle,
@@ -67,26 +60,36 @@ public class DragButtonCalibrationActivity extends Activity {
 
 		setContentView(R.layout.drag_button_calibration);
 
-		final DragButton calibrationButton = (DragButton) findViewById(R.id.calibrationButton);
-		calibrationButton.setOnDragListener(new CalibrationOnDragListener());
-
-		calibrationArrow = (ImageView) findViewById(R.id.calibrationArrow);
-
-		createDragDirection(0);
+		createCalibrationButton(R.id.calibrationButtonRight, R.id.calibrationArrowRight);
+		createCalibrationButton(R.id.calibrationButtonLeft, R.id.calibrationArrowLeft);
 	}
 
-	private void createDragDirection(long timeout) {
+	private void createCalibrationButton(int buttonId, int arrowId) {
+		final DragButton calibrationButton = (DragButton) findViewById(buttonId);
+		calibrationButton.setOnDragListener(new CalibrationOnDragListener());
+
+		ImageView imageView = (ImageView) findViewById(arrowId);
+		CalibrationArrow calibrationArrow = new CalibrationArrow(imageView);
+
+		createDragDirection(0, calibrationArrow);
+
+		map.put(calibrationButton, calibrationArrow);
+	}
+
+	private void createDragDirection(long timeout, @NotNull final CalibrationArrow calibrationArrow) {
 		new Handler().postDelayed(new Runnable() {
 			public void run() {
-				dragDirection = Math.random() > 0.5 ? DragDirection.up : DragDirection.down;
+				calibrationArrow.dragDirection = Math.random() > 0.5 ? DragDirection.up : DragDirection.down;
 
-				calibrationArrow.setImageResource(dragDirection == DragDirection.down ? R.drawable.down : R.drawable.up);
+				calibrationArrow.calibrationArrow.setImageResource(calibrationArrow.dragDirection == DragDirection.down ? R.drawable.down : R.drawable.up);
 			}
 		}, timeout);
 	}
 
 	public void restartClickHandler(View v) {
-		createDragDirection(0);
+		for (CalibrationArrow calibrationArrow : map.values()) {
+			createDragDirection(0, calibrationArrow);
+		}
 	}
 
 
@@ -109,6 +112,9 @@ public class DragButtonCalibrationActivity extends Activity {
 
 			double angle = Math.toDegrees(MathUtils.getAngle(startPoint, MathUtils.sum(startPoint, SimpleOnDragListener.axis), endPoint));
 
+			final CalibrationArrow calibrationArrow = map.get(dragButton);
+			final DragDirection dragDirection = calibrationArrow.dragDirection;
+
 			assert dragDirection == DragDirection.up || dragDirection == DragDirection.down;
 
 			double deviationAngle = angle;
@@ -117,13 +123,13 @@ public class DragButtonCalibrationActivity extends Activity {
 			}
 
 			if (deviationAngle > 45) {
-				calibrationArrow.setImageResource(R.drawable.not_ok);
+				calibrationArrow.calibrationArrow.setImageResource(R.drawable.not_ok);
 			} else {
-				calibrationArrow.setImageResource(R.drawable.ok);
+				calibrationArrow.calibrationArrow.setImageResource(R.drawable.ok);
 				dragHistory.add(new DragData(dragDirection, distance, angle, (motionEvent.getEventTime() - motionEvent.getDownTime())));
 			}
 
-			createDragDirection(500);
+			createDragDirection(500, calibrationArrow);
 
 			return true;
 		}
@@ -372,4 +378,16 @@ public class DragButtonCalibrationActivity extends Activity {
 			return time;
 		}
 	}
+
+	private class CalibrationArrow {
+		@NotNull
+		private ImageView calibrationArrow;
+
+		@NotNull
+		private DragDirection dragDirection = DragDirection.up;
+
+		private CalibrationArrow(@NotNull ImageView calibrationArrow) {
+			this.calibrationArrow = calibrationArrow;
+		}
+	}
 }
diff --git a/src/org/solovyev/android/view/ColorButton.java b/src/org/solovyev/android/view/ColorButton.java
new file mode 100644
index 00000000..13ea5f43
--- /dev/null
+++ b/src/org/solovyev/android/view/ColorButton.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.solovyev.android.view;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.Paint.Style;
+import android.util.AttributeSet;
+import android.widget.Button;
+import android.view.MotionEvent;
+import android.content.res.Resources;
+import org.jetbrains.annotations.NotNull;
+import org.solovyev.android.calculator.R;
+import org.solovyev.util.StringUtils;
+import org.solovyev.util.math.Point2d;
+
+/**
+ * NOTE: copied from com.android.calculator2.ColorButton
+ */
+
+/**
+ * Button with click-animation effect.
+ */
+public class ColorButton extends Button {
+	int CLICK_FEEDBACK_COLOR;
+	static final int CLICK_FEEDBACK_INTERVAL = 10;
+	static final int CLICK_FEEDBACK_DURATION = 350;
+
+	@NotNull
+	private Point2d textPosition;
+	private long mAnimStart;
+	private Paint mFeedbackPaint;
+
+	public ColorButton(Context context, AttributeSet attrs) {
+		this(context, attrs, true);
+	}
+
+	public ColorButton(Context context, AttributeSet attrs, boolean init) {
+		super(context, attrs);
+		if (init) {
+			init(context);
+		}
+	}
+
+	protected void init(Context context) {
+		Resources res = getResources();
+
+		CLICK_FEEDBACK_COLOR = res.getColor(R.color.magic_flame);
+		mFeedbackPaint = new Paint();
+		mFeedbackPaint.setStyle(Style.STROKE);
+		mFeedbackPaint.setStrokeWidth(2);
+		getPaint().setColor(res.getColor(R.color.button_text));
+
+		mAnimStart = -1;
+
+		if (context instanceof FontSizeAdjuster) {
+			((FontSizeAdjuster) context).adjustFontSize(this);
+		}
+	}
+
+
+	@Override
+	public void onSizeChanged(int w, int h, int oldW, int oldH) {
+		measureText();
+	}
+
+	protected void measureText() {
+		Paint paint = getPaint();
+
+		if (getText() != null) {
+			textPosition = getTextPosition(paint, getText());
+		}
+	}
+
+	private Point2d getTextPosition(@NotNull Paint paint, @NotNull CharSequence text) {
+		final Point2d result = new Point2d();
+
+		result.setX((getWidth() - paint.measureText(text.toString())) / 2);
+
+		float height = getHeight() - paint.ascent() - paint.descent();
+
+		result.setY(height / 2);
+
+		return result;
+	}
+
+	@Override
+	protected void onTextChanged(CharSequence text, int start, int before, int after) {
+		measureText();
+	}
+
+	private void drawMagicFlame(int duration, Canvas canvas) {
+		int alpha = 255 - 255 * duration / CLICK_FEEDBACK_DURATION;
+		int color = CLICK_FEEDBACK_COLOR | (alpha << 24);
+
+		mFeedbackPaint.setColor(color);
+		canvas.drawRect(1, 1, getWidth() - 1, getHeight() - 1, mFeedbackPaint);
+	}
+
+	@Override
+	public void onDraw(Canvas canvas) {
+		if (mAnimStart != -1) {
+			int animDuration = (int) (System.currentTimeMillis() - mAnimStart);
+
+			if (animDuration >= CLICK_FEEDBACK_DURATION) {
+				mAnimStart = -1;
+			} else {
+				drawMagicFlame(animDuration, canvas);
+				postInvalidateDelayed(CLICK_FEEDBACK_INTERVAL);
+			}
+		} else if (isPressed()) {
+			drawMagicFlame(0, canvas);
+		}
+
+		CharSequence text = getText();
+		if (text != null && textPosition != null) {
+			canvas.drawText(text, 0, text.length(), textPosition.getX(), textPosition.getY(), getPaint());
+		}
+	}
+
+	public void animateClickFeedback() {
+		mAnimStart = System.currentTimeMillis();
+		invalidate();
+	}
+
+	@Override
+	public boolean onTouchEvent(MotionEvent event) {
+		boolean result = super.onTouchEvent(event);
+
+		switch (event.getAction()) {
+			case MotionEvent.ACTION_UP:
+				animateClickFeedback();
+				break;
+			case MotionEvent.ACTION_DOWN:
+			case MotionEvent.ACTION_CANCEL:
+				invalidate();
+				break;
+		}
+
+		return result;
+	}
+}
diff --git a/src/org/solovyev/android/view/DirectionDragButton.java b/src/org/solovyev/android/view/DirectionDragButton.java
index 761e212a..9828a844 100644
--- a/src/org/solovyev/android/view/DirectionDragButton.java
+++ b/src/org/solovyev/android/view/DirectionDragButton.java
@@ -2,12 +2,16 @@ package org.solovyev.android.view;
 
 import android.content.Context;
 import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.Paint;
 import android.text.Html;
+import android.text.TextPaint;
 import android.util.AttributeSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.R;
 import org.solovyev.util.StringUtils;
+import org.solovyev.util.math.Point2d;
 
 /**
  * User: serso
@@ -25,15 +29,20 @@ public class DirectionDragButton extends DragButton {
 	@Nullable
 	private String textMiddle;
 
+	@NotNull
+	private Point2d textUpPosition;
+
+	@NotNull
+	private Point2d textDownPosition;
+
+	@NotNull
+	private TextPaint upDownTextPaint;
+
 	public DirectionDragButton(Context context, @NotNull AttributeSet attrs) {
-		super(context, attrs);
+		super(context, attrs, false);
 		init(context, attrs);
 	}
 
-	public DirectionDragButton(Context context, AttributeSet attrs, int defStyle) {
-		super(context, attrs, defStyle);
-		init(context, attrs);
-	}
 
 	private void init(@NotNull Context context, @NotNull AttributeSet attrs) {
 
@@ -55,19 +64,81 @@ public class DirectionDragButton extends DragButton {
 		// backup text
 		this.textMiddle = String.valueOf(getText());
 
-		setText(Html.fromHtml(getStyledUpDownText(this.textUp) + "<br><b>" + StringUtils.getNotEmpty(this.textMiddle, "&nbsp;") + "</b><br>" + getStyledUpDownText(this.textDown)));
+		super.init(context);
+	}
 
-		// change top padding in order to show all text
-		setPadding(getPaddingLeft(), -7, getPaddingRight(), getPaddingBottom());
+	@Override
+	protected void measureText() {
+		super.measureText();
+
+		final Paint basePaint = getPaint();
+		initUpDownTextPaint(basePaint);
+
+		if (textUp != null) {
+			textUpPosition = getTextPosition(upDownTextPaint, basePaint, textUp, 1);
+		}
+
+		if (textDown != null) {
+			textDownPosition = getTextPosition(upDownTextPaint, basePaint, textDown, -1);
+		}
+
+		if ( textDownPosition != null && textUpPosition != null ) {
+			if ( textDownPosition.getX() > textUpPosition.getX() ) {
+				textDownPosition.setX(textUpPosition.getX());
+			} else {
+				textUpPosition.setX(textDownPosition.getX());
+			}
+		}
+
+	}
+
+	private Point2d getTextPosition(@NotNull Paint paint, @NotNull Paint basePaint, @NotNull CharSequence text, float direction) {
+		final Point2d result = new Point2d();
+
+		float width = paint.measureText(text.toString() + " ");
+		result.setX(getWidth() - width);
+
+		float selfHeight = paint.ascent() + paint.descent();
+
+		basePaint.measureText(StringUtils.getNotEmpty(getText(), "|"));
+
+		float height = getHeight() - basePaint.ascent() - basePaint.descent();
+		if (direction < 0) {
+			result.setY(height / 2 - direction * height / 3 + selfHeight);
+		} else {
+			result.setY(height / 2 - direction * height / 3);
+		}
+
+		return result;
+	}
+
+	@Override
+	public void onDraw(Canvas canvas) {
+		super.onDraw(canvas);
+
+		initUpDownTextPaint(null);
+
+		if (textUp != null && textUpPosition != null) {
+			canvas.drawText(textUp, 0, textUp.length(), textUpPosition.getX(), textUpPosition.getY(), upDownTextPaint);
+		}
+
+		if (textDown != null && textDownPosition != null) {
+			canvas.drawText(textDown, 0, textDown.length(), textDownPosition.getX(), textDownPosition.getY(), upDownTextPaint);
+		}
+	}
+
+	private void initUpDownTextPaint(@Nullable Paint paint) {
+		if (paint == null) {
+			paint = getPaint();
+		}
+
+		upDownTextPaint = new TextPaint(paint);
+		upDownTextPaint.setAlpha(150);
+		upDownTextPaint.setTextSize(paint.getTextSize() / 2);
 	}
 
 	private String getStyledUpDownText(@Nullable String text) {
-		final StringBuilder sb = new StringBuilder();
-
-		sb.append("<font color='#585858'><small><small>");
-		sb.append(StringUtils.getNotEmpty(text, "&nbsp;"));
-		sb.append("</small></small></font>");
-		return sb.toString();
+		return StringUtils.getNotEmpty(text, "&nbsp;");
 	}
 
 	public void setTextUp(@Nullable String textUp) {
diff --git a/src/org/solovyev/android/view/DragButton.java b/src/org/solovyev/android/view/DragButton.java
index 6c5e99a2..f1347fe3 100644
--- a/src/org/solovyev/android/view/DragButton.java
+++ b/src/org/solovyev/android/view/DragButton.java
@@ -2,22 +2,15 @@ package org.solovyev.android.view;
 
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.solovyev.android.calculator.R;
-import org.solovyev.common.utils.StringsUtils;
-import org.solovyev.util.StringUtils;
-import org.solovyev.util.math.MathUtils;
 import org.solovyev.util.math.Point2d;
 
 import android.content.Context;
-import android.content.res.TypedArray;
-import android.text.Html;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
-import android.widget.Button;
 
-public class DragButton extends Button {
+public class DragButton extends ColorButton {
 
 	@Nullable
 	private Point2d startPoint = null;
@@ -28,13 +21,15 @@ public class DragButton extends Button {
 	private final OnTouchListener onTouchListener = new OnTouchListenerImpl();
 
 	public DragButton(Context context, @NotNull AttributeSet attrs) {
-		super(context, attrs);
-		setOnTouchListener(this.onTouchListener);
+		this(context, attrs, true);
 	}
 
-	public DragButton(Context context, AttributeSet attrs, int defStyle) {
-		super(context, attrs, defStyle);
+	public DragButton(Context context, @NotNull AttributeSet attrs, boolean init) {
+		super(context, attrs, false);
 		setOnTouchListener(this.onTouchListener);
+		if ( init ) {
+			super.init(context);
+		}
 	}
 
 	public void setOnDragListener(@Nullable OnDragListener onDragListener) {
diff --git a/src/org/solovyev/android/view/FontSizeAdjuster.java b/src/org/solovyev/android/view/FontSizeAdjuster.java
new file mode 100644
index 00000000..932b6272
--- /dev/null
+++ b/src/org/solovyev/android/view/FontSizeAdjuster.java
@@ -0,0 +1,14 @@
+package org.solovyev.android.view;
+
+import android.widget.TextView;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * User: serso
+ * Date: 9/10/11
+ * Time: 7:21 PM
+ */
+public interface FontSizeAdjuster {
+
+    void adjustFontSize(@NotNull TextView textView);
+}
diff --git a/src/org/solovyev/android/view/PanelSwitcher.java b/src/org/solovyev/android/view/PanelSwitcher.java
new file mode 100644
index 00000000..b8719de9
--- /dev/null
+++ b/src/org/solovyev/android/view/PanelSwitcher.java
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.solovyev.android.view;
+
+import android.view.animation.TranslateAnimation;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.GestureDetector;
+import android.widget.FrameLayout;
+import android.content.Context;
+import android.util.AttributeSet;
+
+class PanelSwitcher extends FrameLayout {
+    private static final int MAJOR_MOVE = 60;
+    private static final int ANIM_DURATION = 400;
+
+    private GestureDetector mGestureDetector;
+    private int mCurrentView;
+    private View mChildren[] = new View[0];
+
+    private int mWidth;
+    private TranslateAnimation inLeft;
+    private TranslateAnimation outLeft;
+
+    private TranslateAnimation inRight;
+    private TranslateAnimation outRight;
+
+    private static final int LEFT  = 1;
+    private static final int RIGHT = 2;
+    private int mPreviousMove;
+
+    public PanelSwitcher(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        mCurrentView = 0;
+        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
+                public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
+                                       float velocityY) {
+                    int dx = (int) (e2.getX() - e1.getX());
+
+                    // don't accept the fling if it's too short
+                    // as it may conflict with a button push
+                    if (Math.abs(dx) > MAJOR_MOVE && Math.abs(velocityX) > Math.abs(velocityY)) {
+                        if (velocityX > 0) {
+                            moveRight();
+                        } else {
+                            moveLeft();
+                        }
+                        return true;
+                    } else {
+                        return false;
+                    }
+                }
+            });
+    }
+
+    void setCurrentIndex(int current) {
+        mCurrentView = current;
+        updateCurrentView();
+    }
+
+    private void updateCurrentView() {
+        for (int i = mChildren.length-1; i >= 0 ; --i) {
+            mChildren[i].setVisibility(i==mCurrentView ? View.VISIBLE : View.GONE);
+        }
+    }
+
+    @Override 
+    public void onSizeChanged(int w, int h, int oldW, int oldH) {
+        mWidth = w;
+        inLeft   = new TranslateAnimation(mWidth, 0, 0, 0);
+        outLeft  = new TranslateAnimation(0, -mWidth, 0, 0);        
+        inRight  = new TranslateAnimation(-mWidth, 0, 0, 0);
+        outRight = new TranslateAnimation(0, mWidth, 0, 0);
+
+        inLeft.setDuration(ANIM_DURATION);
+        outLeft.setDuration(ANIM_DURATION);
+        inRight.setDuration(ANIM_DURATION);
+        outRight.setDuration(ANIM_DURATION);
+    }
+
+    protected void onFinishInflate() {
+        int count = getChildCount();
+        mChildren = new View[count];
+        for (int i = 0; i < count; ++i) {
+            mChildren[i] = getChildAt(i);
+        }
+        updateCurrentView();
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        mGestureDetector.onTouchEvent(event);
+        return true;
+    }
+
+    @Override
+    public boolean onInterceptTouchEvent(MotionEvent event) {
+        return mGestureDetector.onTouchEvent(event);
+    }
+
+    void moveLeft() {
+        //  <--
+        if (mCurrentView < mChildren.length - 1 && mPreviousMove != LEFT) {
+            mChildren[mCurrentView+1].setVisibility(View.VISIBLE);
+            mChildren[mCurrentView+1].startAnimation(inLeft);
+            mChildren[mCurrentView].startAnimation(outLeft);
+            mChildren[mCurrentView].setVisibility(View.GONE);
+
+            mCurrentView++;
+            mPreviousMove = LEFT;
+        }
+    }
+
+    void moveRight() {
+        //  -->
+        if (mCurrentView > 0 && mPreviousMove != RIGHT) {
+            mChildren[mCurrentView-1].setVisibility(View.VISIBLE);
+            mChildren[mCurrentView-1].startAnimation(inRight);
+            mChildren[mCurrentView].startAnimation(outRight);
+            mChildren[mCurrentView].setVisibility(View.GONE);
+
+            mCurrentView--;
+            mPreviousMove = RIGHT;
+        }
+    }
+
+    int getCurrentIndex() {
+        return mCurrentView;
+    }
+}
diff --git a/src/org/solovyev/util/StringUtils.java b/src/org/solovyev/util/StringUtils.java
index dd37f27f..62dda574 100644
--- a/src/org/solovyev/util/StringUtils.java
+++ b/src/org/solovyev/util/StringUtils.java
@@ -5,13 +5,13 @@ import org.jetbrains.annotations.Nullable;
 
 public class StringUtils {
 
-	public static boolean isEmpty ( @Nullable String s ){
+	public static boolean isEmpty ( @Nullable CharSequence s ){
 		return s == null || s.length() == 0;
 	}
 	
 	@NotNull
-	public static String getNotEmpty ( @Nullable String s, @NotNull String defaultValue ){
-		return isEmpty(s) ? defaultValue : s;
+	public static String getNotEmpty ( @Nullable CharSequence s, @NotNull String defaultValue ){
+		return isEmpty(s) ? defaultValue : s.toString();
 	}
 }