diff --git a/app/src/main/java/org/solovyev/android/calculator/FloatingCalculatorKeyboard.java b/app/src/main/java/org/solovyev/android/calculator/FloatingCalculatorKeyboard.java
index c47d4778..532cb8da 100644
--- a/app/src/main/java/org/solovyev/android/calculator/FloatingCalculatorKeyboard.java
+++ b/app/src/main/java/org/solovyev/android/calculator/FloatingCalculatorKeyboard.java
@@ -9,10 +9,7 @@ import android.widget.LinearLayout;
 import org.solovyev.android.calculator.keyboard.BaseFloatingKeyboard;
 import org.solovyev.android.calculator.keyboard.FloatingKeyboard;
 import org.solovyev.android.calculator.view.EditTextLongClickEraser;
-import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DirectionDragListener;
-import org.solovyev.android.views.dragbutton.DragDirection;
-import org.solovyev.android.views.dragbutton.DragEvent;
+import org.solovyev.android.views.dragbutton.*;
 
 import java.util.List;
 
@@ -35,7 +32,7 @@ public class FloatingCalculatorKeyboard extends BaseFloatingKeyboard {
         this.dragListener = new DirectionDragListener(user.getContext()) {
             @Override
             protected boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction) {
-                return buttonHandler.onDrag(view, direction);
+                return Drag.hasDirectionText(view, direction) && buttonHandler.onDrag(view, direction);
             }
         };
     }
diff --git a/app/src/main/java/org/solovyev/android/calculator/Preferences.java b/app/src/main/java/org/solovyev/android/calculator/Preferences.java
index bd1f35c9..e7bbd734 100644
--- a/app/src/main/java/org/solovyev/android/calculator/Preferences.java
+++ b/app/src/main/java/org/solovyev/android/calculator/Preferences.java
@@ -83,7 +83,6 @@ public final class Preferences {
             migratePreference(preferences, editor, Gui.layout, Deleted.layout);
             migratePreference(preferences, editor, Gui.useBackAsPrevious, Deleted.usePrevAsBack);
             migratePreference(preferences, editor, Gui.showReleaseNotes, Deleted.showReleaseNotes);
-            migratePreference(preferences, editor, Gui.showEqualsButton, Deleted.showEqualsButton);
             migratePreference(preferences, editor, Gui.rotateScreen, Deleted.autoOrientation);
             final Gui.Layout layout = Deleted.layout.getPreference(preferences);
             if (layout == Gui.Layout.main_cellphone) {
@@ -137,7 +136,6 @@ public final class Preferences {
         Gui.layout.tryPutDefault(preferences, editor);
         Gui.showReleaseNotes.tryPutDefault(preferences, editor);
         Gui.useBackAsPrevious.tryPutDefault(preferences, editor);
-        Gui.showEqualsButton.tryPutDefault(preferences, editor);
         Gui.rotateScreen.tryPutDefault(preferences, editor);
         Gui.keepScreenOn.tryPutDefault(preferences, editor);
         Gui.language.tryPutDefault(preferences, editor);
diff --git a/app/src/main/java/org/solovyev/android/calculator/keyboard/BaseKeyboardUi.java b/app/src/main/java/org/solovyev/android/calculator/keyboard/BaseKeyboardUi.java
index f8f9efb9..3bbcdaf9 100644
--- a/app/src/main/java/org/solovyev/android/calculator/keyboard/BaseKeyboardUi.java
+++ b/app/src/main/java/org/solovyev/android/calculator/keyboard/BaseKeyboardUi.java
@@ -12,35 +12,20 @@ import android.util.TypedValue;
 import android.view.View;
 import android.widget.ImageView;
 import android.widget.TextView;
-
-import org.solovyev.android.calculator.ActivityLauncher;
-import org.solovyev.android.calculator.App;
-import org.solovyev.android.calculator.BaseActivity;
-import org.solovyev.android.calculator.Calculator;
-import org.solovyev.android.calculator.Editor;
-import org.solovyev.android.calculator.Keyboard;
-import org.solovyev.android.calculator.Preferences;
-import org.solovyev.android.calculator.PreferredPreferences;
+import dagger.Lazy;
+import org.solovyev.android.calculator.*;
 import org.solovyev.android.calculator.buttons.CppSpecialButton;
+import org.solovyev.android.calculator.memory.Memory;
 import org.solovyev.android.views.Adjuster;
-import org.solovyev.android.views.dragbutton.DirectionDragButton;
-import org.solovyev.android.views.dragbutton.DirectionDragImageButton;
-import org.solovyev.android.views.dragbutton.DirectionDragListener;
-import org.solovyev.android.views.dragbutton.DirectionDragView;
-import org.solovyev.android.views.dragbutton.DragDirection;
-import org.solovyev.android.views.dragbutton.DragEvent;
-import org.solovyev.android.views.dragbutton.DragView;
-
-import java.util.ArrayList;
-import java.util.List;
+import org.solovyev.android.views.dragbutton.*;
 
 import javax.annotation.Nonnull;
 import javax.inject.Inject;
+import java.util.ArrayList;
+import java.util.List;
 
 import static android.content.res.Configuration.ORIENTATION_PORTRAIT;
-import static android.view.HapticFeedbackConstants.FLAG_IGNORE_GLOBAL_SETTING;
-import static android.view.HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING;
-import static android.view.HapticFeedbackConstants.KEYBOARD_TAP;
+import static android.view.HapticFeedbackConstants.*;
 import static org.solovyev.android.calculator.App.cast;
 import static org.solovyev.android.calculator.Preferences.Gui.Layout.simple;
 import static org.solovyev.android.calculator.Preferences.Gui.Layout.simple_mobile;
@@ -71,6 +56,8 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
     @Inject
     ActivityLauncher launcher;
     @Inject
+    Lazy<Memory> memory;
+    @Inject
     PreferredPreferences preferredPreferences;
     protected int orientation = ORIENTATION_PORTRAIT;
     private int textSize;
@@ -81,7 +68,7 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
         listener = new DirectionDragListener(application) {
             @Override
             protected boolean onDrag(@NonNull View view, @NonNull DragEvent event, @NonNull DragDirection direction) {
-                return BaseKeyboardUi.this.onDrag(view, direction);
+                return Drag.hasDirectionText(view, direction) && BaseKeyboardUi.this.onDrag(view, direction);
             }
         };
         textScale = getTextScale(application);
@@ -136,6 +123,8 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
         prepareButton((ImageView) button);
         button.setOnDragListener(listener);
         button.setTypeface(typeface);
+        button.setTextSize(textSize);
+        Adjuster.adjustText(button, AdjusterHelper.instance, textScale, 0);
     }
 
     protected final void prepareButton(@Nullable DirectionDragButton button) {
@@ -209,4 +198,19 @@ public abstract class BaseKeyboardUi implements SharedPreferences.OnSharedPrefer
     protected final void onClick(@Nonnull View v, @Nonnull CppSpecialButton b) {
         onClick(v, b.action);
     }
+
+    private static class AdjusterHelper implements Adjuster.Helper<DirectionDragImageButton> {
+
+        public static AdjusterHelper instance = new AdjusterHelper();
+
+        @Override
+        public void apply(@NonNull DirectionDragImageButton view, float textSize) {
+            view.setTextSize(textSize);
+        }
+
+        @Override
+        public float getTextSize(@NonNull DirectionDragImageButton view) {
+            return view.getTextSize();
+        }
+    }
 }
diff --git a/app/src/main/java/org/solovyev/android/calculator/keyboard/KeyboardUi.java b/app/src/main/java/org/solovyev/android/calculator/keyboard/KeyboardUi.java
index fb21d9e1..18de0617 100644
--- a/app/src/main/java/org/solovyev/android/calculator/keyboard/KeyboardUi.java
+++ b/app/src/main/java/org/solovyev/android/calculator/keyboard/KeyboardUi.java
@@ -10,16 +10,15 @@ import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ImageButton;
-
-import org.solovyev.android.calculator.ActivityLauncher;
-import org.solovyev.android.calculator.App;
-import org.solovyev.android.calculator.Display;
-import org.solovyev.android.calculator.DisplayState;
-import org.solovyev.android.calculator.Engine;
-import org.solovyev.android.calculator.R;
+import butterknife.Bind;
+import butterknife.ButterKnife;
+import jscl.AngleUnit;
+import jscl.NumeralBase;
+import jscl.math.Expression;
+import jscl.math.Generic;
+import org.solovyev.android.calculator.*;
 import org.solovyev.android.calculator.buttons.CppSpecialButton;
 import org.solovyev.android.calculator.history.History;
-import org.solovyev.android.calculator.memory.Memory;
 import org.solovyev.android.calculator.view.AngleUnitsButton;
 import org.solovyev.android.calculator.view.NumeralBasesButton;
 import org.solovyev.android.views.dragbutton.DirectionDragButton;
@@ -30,20 +29,8 @@ import org.solovyev.android.views.dragbutton.DragDirection;
 import javax.annotation.Nonnull;
 import javax.inject.Inject;
 
-import butterknife.Bind;
-import butterknife.ButterKnife;
-import dagger.Lazy;
-import jscl.AngleUnit;
-import jscl.NumeralBase;
-import jscl.math.Expression;
-import jscl.math.Generic;
-
-import static org.solovyev.android.calculator.Engine.Preferences.angleUnit;
-import static org.solovyev.android.calculator.Engine.Preferences.multiplicationSign;
-import static org.solovyev.android.calculator.Engine.Preferences.numeralBase;
-import static org.solovyev.android.views.dragbutton.DragDirection.down;
-import static org.solovyev.android.views.dragbutton.DragDirection.left;
-import static org.solovyev.android.views.dragbutton.DragDirection.up;
+import static org.solovyev.android.calculator.Engine.Preferences.*;
+import static org.solovyev.android.views.dragbutton.DragDirection.*;
 
 public class KeyboardUi extends BaseKeyboardUi {
 
@@ -76,8 +63,6 @@ public class KeyboardUi extends BaseKeyboardUi {
     @Inject
     Display display;
     @Inject
-    Lazy<Memory> memory;
-    @Inject
     PartialKeyboardUi partialUi;
     @Bind(R.id.cpp_button_vars)
     DirectionDragButton variablesButton;
@@ -108,6 +93,9 @@ public class KeyboardUi extends BaseKeyboardUi {
     @Bind(R.id.cpp_button_like)
     ImageButton likeButton;
     @Nullable
+    @Bind(R.id.cpp_button_percent)
+    DirectionDragButton percentButton;
+    @Nullable
     @Bind(R.id.cpp_button_memory)
     DirectionDragButton memoryButton;
 
@@ -143,6 +131,7 @@ public class KeyboardUi extends BaseKeyboardUi {
 
         prepareButton(periodButton);
         prepareButton(bracketsButton);
+        prepareButton(percentButton);
 
         prepareButton(button0);
         prepareButton(button1);
@@ -163,9 +152,9 @@ public class KeyboardUi extends BaseKeyboardUi {
         prepareButton(memoryButton);
 
         if (isSimpleLayout()) {
-            hideText(button1, up, down);
-            hideText(button2, up, down);
-            hideText(button3, up, down);
+            hideText(button1, down);
+            hideText(button2, down);
+            hideText(button3, down);
             hideText(button4, down);
             hideText(button5, down);
             hideText(button7, left, up, down);
@@ -175,6 +164,7 @@ public class KeyboardUi extends BaseKeyboardUi {
             hideText(plusButton, up, down);
             hideText(copyButton, left, up, down);
             hideText(pasteButton, left, up, down);
+            hideText(functionsButton, up, down);
         }
         multiplicationButton.setText(engine.getMultiplicationSign());
         toggleNumericDigits();
@@ -216,6 +206,7 @@ public class KeyboardUi extends BaseKeyboardUi {
             case R.id.cpp_button_9:
             case R.id.cpp_button_division:
             case R.id.cpp_button_period:
+            case R.id.cpp_button_percent:
             case R.id.cpp_button_subtraction:
             case R.id.cpp_button_multiplication:
             case R.id.cpp_button_plus:
@@ -252,13 +243,13 @@ public class KeyboardUi extends BaseKeyboardUi {
     @Override
     protected boolean onDrag(@NonNull View view, @NonNull DragDirection direction) {
         switch (view.getId()) {
-            case R.id.cpp_button_vars:
-                launcher.showConstantEditor();
-                return true;
             case R.id.cpp_button_functions:
                 if (direction == up) {
                     launcher.showFunctionEditor();
                     return true;
+                } else if (direction == down) {
+                    launcher.showConstantEditor();
+                    return true;
                 }
                 return false;
             case R.id.cpp_button_history:
@@ -272,12 +263,6 @@ public class KeyboardUi extends BaseKeyboardUi {
                 return false;
             case R.id.cpp_button_memory:
                 return processMemoryButton(direction);
-            case R.id.cpp_button_subtraction:
-                if (direction == down) {
-                    launcher.showOperators();
-                    return true;
-                }
-                return false;
             case R.id.cpp_button_copy:
                 return processNumeralBaseButton(direction, (DirectionDragView) view);
             case R.id.cpp_button_paste:
@@ -307,6 +292,7 @@ public class KeyboardUi extends BaseKeyboardUi {
             }
         }
         if (value == null) {
+            memory.get().show();
             return false;
         }
         switch (direction) {
@@ -316,9 +302,6 @@ public class KeyboardUi extends BaseKeyboardUi {
             case down:
                 memory.get().subtract(value);
                 return true;
-            case left:
-                memory.get().clear();
-                return true;
         }
         return false;
     }
diff --git a/app/src/main/java/org/solovyev/android/calculator/keyboard/PartialKeyboardUi.java b/app/src/main/java/org/solovyev/android/calculator/keyboard/PartialKeyboardUi.java
index 1e11a8c6..42887091 100644
--- a/app/src/main/java/org/solovyev/android/calculator/keyboard/PartialKeyboardUi.java
+++ b/app/src/main/java/org/solovyev/android/calculator/keyboard/PartialKeyboardUi.java
@@ -3,14 +3,12 @@ package org.solovyev.android.calculator.keyboard;
 import android.app.Activity;
 import android.app.Application;
 import android.content.SharedPreferences;
-import android.content.res.Configuration;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.view.View;
-import android.widget.Button;
 import android.widget.ImageButton;
-
-import org.solovyev.android.calculator.Preferences;
+import butterknife.Bind;
+import butterknife.ButterKnife;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.buttons.CppSpecialButton;
 import org.solovyev.android.calculator.view.EditorLongClickEraser;
@@ -21,10 +19,6 @@ import org.solovyev.android.views.dragbutton.DragDirection;
 import javax.annotation.Nonnull;
 import javax.inject.Inject;
 
-import butterknife.Bind;
-import butterknife.ButterKnife;
-
-import static org.solovyev.android.calculator.Preferences.Gui.showEqualsButton;
 import static org.solovyev.android.calculator.Preferences.Gui.vibrateOnKeypress;
 import static org.solovyev.android.views.dragbutton.DragDirection.down;
 import static org.solovyev.android.views.dragbutton.DragDirection.up;
@@ -39,7 +33,7 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
     DirectionDragImageButton leftButton;
     @Nullable
     @Bind(R.id.cpp_button_clear)
-    Button clearButton;
+    DirectionDragButton clearButton;
     @Nullable
     @Bind(R.id.cpp_button_erase)
     ImageButton eraseButton;
@@ -67,30 +61,14 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
             prepareButton(eraseButton, IMAGE_SCALE_ERASE);
             longClickEraser = EditorLongClickEraser.attachTo(eraseButton, keyboard.isVibrateOnKeypress(), editor, calculator);
         }
-        toggleEqualsButton();
-    }
-
-    public void toggleEqualsButton() {
-        if (equalsButton == null) {
-            return;
-        }
-        if (orientation != Configuration.ORIENTATION_PORTRAIT && Preferences.Gui.rotateScreen.getPreference(preferences)) {
-            return;
-        }
-
-        if (Preferences.Gui.showEqualsButton.getPreference(preferences)) {
-            equalsButton.setVisibility(View.VISIBLE);
-        } else {
-            equalsButton.setVisibility(View.GONE);
+        if(isSimpleLayout()) {
+            hideText(equalsButton, down);
         }
     }
 
     @Override
     public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
         super.onSharedPreferenceChanged(preferences, key);
-        if (equalsButton != null && showEqualsButton.isSameKey(key)) {
-            toggleEqualsButton();
-        }
         if (longClickEraser != null && vibrateOnKeypress.isSameKey(key)) {
             longClickEraser.setVibrateOnKeypress(vibrateOnKeypress.getPreference(preferences));
         }
@@ -105,6 +83,12 @@ public class PartialKeyboardUi extends BaseKeyboardUi {
             case R.id.cpp_button_left:
                 editor.setCursorOnStart();
                 return true;
+            case R.id.cpp_button_clear:
+                if(direction == up) {
+                    memory.get().clear();
+                    return true;
+                }
+                return false;
             case R.id.cpp_button_equals:
                 if (direction == down) {
                     launcher.plotDisplayedExpression();
diff --git a/app/src/main/java/org/solovyev/android/calculator/memory/Memory.java b/app/src/main/java/org/solovyev/android/calculator/memory/Memory.java
index 14f0be53..0f6aa8c1 100644
--- a/app/src/main/java/org/solovyev/android/calculator/memory/Memory.java
+++ b/app/src/main/java/org/solovyev/android/calculator/memory/Memory.java
@@ -156,6 +156,10 @@ public class Memory {
         value = numeric(newValue);
         handler.removeCallbacks(writeTask);
         handler.postDelayed(writeTask, 3000L);
+        show();
+    }
+
+    public void show() {
         notifier.showMessage(getValue());
     }
 
diff --git a/app/src/main/java/org/solovyev/android/views/Adjuster.java b/app/src/main/java/org/solovyev/android/views/Adjuster.java
index e6fd0292..e3bc93ef 100644
--- a/app/src/main/java/org/solovyev/android/views/Adjuster.java
+++ b/app/src/main/java/org/solovyev/android/views/Adjuster.java
@@ -16,17 +16,33 @@ import static android.graphics.Matrix.MSCALE_Y;
 public class Adjuster {
 
     private static final float[] MATRIX = new float[9];
+    @NonNull
+    private static Helper<TextView> textViewHelper = new Helper<TextView>() {
+        @Override
+        public void apply(@NonNull TextView view, float textSize) {
+            view.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);
+        }
+
+        @Override
+        public float getTextSize(@NonNull TextView view) {
+            return view.getTextSize();
+        }
+    };
 
     public static void adjustText(@NonNull final TextView view, final float percentage) {
-        adjustText(view, percentage, 0);
+        adjustText(view, textViewHelper, percentage, 0);
     }
 
-    public static void adjustText(@NonNull final TextView view, final float percentage, final float minTextSizePxs) {
+    public static void adjustText(@NonNull final TextView view, final float percentage, int minTextSizePxs) {
+        adjustText(view, textViewHelper, percentage, minTextSizePxs);
+    }
+
+    public static <V extends View> void adjustText(@NonNull final V view, @NonNull Helper<V> helper, final float percentage, final float minTextSizePxs) {
         ViewTreeObserver treeObserver = getTreeObserver(view);
         if (treeObserver == null) {
             return;
         }
-        treeObserver.addOnPreDrawListener(new TextViewAdjuster(view, percentage, minTextSizePxs));
+        treeObserver.addOnPreDrawListener(new TextViewAdjuster<V>(view, helper, percentage, minTextSizePxs));
     }
 
     @Nullable
@@ -57,6 +73,12 @@ public class Adjuster {
         treeObserver.addOnPreDrawListener(new MaxWidthAdjuster(view, maxWidth));
     }
 
+    public interface Helper<V extends View> {
+        void apply(@NonNull V view, float textSize);
+
+        float getTextSize(@NonNull V view);
+    }
+
     private static abstract class BaseViewAdjuster<V extends View> implements ViewTreeObserver.OnPreDrawListener {
         @NonNull
         protected final V view;
@@ -82,24 +104,26 @@ public class Adjuster {
         protected abstract boolean adjust(int width, int height);
     }
 
-    private static class TextViewAdjuster extends BaseViewAdjuster<TextView> {
+    private static class TextViewAdjuster<V extends View> extends BaseViewAdjuster<V> {
         private final float percentage;
         private final float minTextSizePxs;
+        private final Helper<V> helper;
 
-        public TextViewAdjuster(@NonNull TextView view, float percentage, float minTextSizePxs) {
+        public TextViewAdjuster(@NonNull V view, @NonNull Helper<V> helper, float percentage, float minTextSizePxs) {
             super(view);
+            this.helper = helper;
             this.percentage = percentage;
             this.minTextSizePxs = minTextSizePxs;
         }
 
         @Override
         protected boolean adjust(int width, int height) {
-            final float oldTextSize = Math.round(view.getTextSize());
+            final float oldTextSize = Math.round(helper.getTextSize(view));
             final float newTextSize = Math.max(minTextSizePxs, Math.round(height * percentage));
             if (oldTextSize == newTextSize) {
                 return true;
             }
-            view.setTextSize(TypedValue.COMPLEX_UNIT_PX, newTextSize);
+            helper.apply(view, newTextSize);
             return false;
         }
     }
diff --git a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragButton.java b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragButton.java
index 75338e8d..b3d8b1ed 100644
--- a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragButton.java
+++ b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragButton.java
@@ -41,20 +41,16 @@ public class DirectionDragButton extends DragButton implements DirectionDragView
     }
 
     @Override
-    public boolean onPreDraw() {
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
         final TextPaint paint = getPaint();
         if (baseTextPaint.getTextSize() != paint.getTextSize() ||
+                baseTextPaint.getTypeface() != paint.getTypeface() ||
                 baseTextPaint.getColor() != paint.getColor() ||
                 baseTextPaint.getAlpha() != paint.getAlpha()) {
             baseTextPaint.set(paint);
             textView.setBaseTextPaint(paint);
         }
-        return super.onPreDraw();
-    }
-
-    @Override
-    protected void onDraw(Canvas canvas) {
-        super.onDraw(canvas);
         textView.draw(canvas);
     }
 
diff --git a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragImageButton.java b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragImageButton.java
index 58bda9eb..9cdc759b 100644
--- a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragImageButton.java
+++ b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionDragImageButton.java
@@ -54,10 +54,19 @@ public class DirectionDragImageButton extends DragImageButton implements Directi
 
     public void setTypeface(@Nonnull Typeface newTypeface) {
         final Typeface oldTypeface = baseTextPaint.getTypeface();
-        if(oldTypeface == newTypeface) {
+        if (oldTypeface == newTypeface) {
             return;
         }
         baseTextPaint.setTypeface(newTypeface);
         textView.setBaseTextPaint(baseTextPaint);
     }
+
+    public void setTextSize(float textSizePxs) {
+        baseTextPaint.setTextSize(textSizePxs);
+        textView.setBaseTextPaint(baseTextPaint);
+    }
+
+    public float getTextSize() {
+        return baseTextPaint.getTextSize();
+    }
 }
diff --git a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionTextView.java b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionTextView.java
index 0e997b71..3de23fb9 100644
--- a/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionTextView.java
+++ b/app/src/main/java/org/solovyev/android/views/dragbutton/DirectionTextView.java
@@ -127,7 +127,10 @@ public class DirectionTextView {
             paint.set(base);
             paint.setColor(color);
             paint.setAlpha(intAlpha());
-            paint.setTypeface(Typeface.DEFAULT);
+            final Typeface typeface = base.getTypeface();
+            if (typeface != null && typeface.getStyle() != Typeface.NORMAL) {
+                paint.setTypeface(Typeface.create(typeface, Typeface.NORMAL));
+            }
 
             // pre-calculate fixed height
             paint.setTextSize(Math.max(base.getTextSize() * DEF_SCALE, minTextSize));
@@ -176,7 +179,7 @@ public class DirectionTextView {
         }
 
         public void draw(@NonNull Canvas canvas) {
-            if (!visible || TextUtils.isEmpty(value)) {
+            if (!hasValue()) {
                 return;
             }
             if (position.x < 0 || position.y < 0) {
@@ -222,6 +225,10 @@ public class DirectionTextView {
             return visible ? value : "";
         }
 
+        public boolean hasValue() {
+            return visible && !TextUtils.isEmpty(value);
+        }
+
         public void setValue(@NonNull String value) {
             if (TextUtils.equals(this.value, value)) {
                 return;
diff --git a/app/src/main/java/org/solovyev/android/views/dragbutton/Drag.java b/app/src/main/java/org/solovyev/android/views/dragbutton/Drag.java
index a499a99b..425ebafe 100644
--- a/app/src/main/java/org/solovyev/android/views/dragbutton/Drag.java
+++ b/app/src/main/java/org/solovyev/android/views/dragbutton/Drag.java
@@ -3,8 +3,9 @@ package org.solovyev.android.views.dragbutton;
 import android.graphics.PointF;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.view.View;
 
-final class Drag {
+public final class Drag {
 
     private Drag() {
     }
@@ -19,6 +20,13 @@ final class Drag {
         return new PointF(p1.x - p2.x, p1.y - p2.y);
     }
 
+    public static boolean hasDirectionText(@NonNull View view, @NonNull DragDirection direction) {
+        if (view instanceof DirectionDragView) {
+            return ((DirectionDragView) view).getText(direction).hasValue();
+        }
+        return false;
+    }
+
     @NonNull
     public static PointF sum(@NonNull PointF p1, @NonNull PointF p2) {
         return new PointF(p1.x + p2.x, p1.y + p2.y);
diff --git a/app/src/main/res/layout-land/activity_main.xml b/app/src/main/res/layout-land/activity_main.xml
index 63f2ba2f..c9ab7aee 100644
--- a/app/src/main/res/layout-land/activity_main.xml
+++ b/app/src/main/res/layout-land/activity_main.xml
@@ -38,13 +38,7 @@
         a:orientation="horizontal">
 
         <include
-            layout="@layout/cpp_app_button_left"
-            a:layout_width="0dp"
-            a:layout_height="match_parent"
-            a:layout_weight="1" />
-
-        <include
-            layout="@layout/cpp_app_button_erase"
+            layout="@layout/cpp_app_button_equals_no_bg"
             a:layout_width="0dp"
             a:layout_height="match_parent"
             a:layout_weight="1" />
@@ -53,17 +47,17 @@
             a:id="@+id/display"
             a:layout_width="0dp"
             a:layout_height="match_parent"
-            a:layout_weight="4"
+            a:layout_weight="5"
             a:orientation="horizontal" />
 
         <include
-            layout="@layout/cpp_app_button_clear"
+            layout="@layout/cpp_app_button_erase"
             a:layout_width="0dp"
             a:layout_height="match_parent"
             a:layout_weight="1" />
 
         <include
-            layout="@layout/cpp_app_button_right"
+            layout="@layout/cpp_app_button_clear"
             a:layout_width="0dp"
             a:layout_height="match_parent"
             a:layout_weight="1" />
diff --git a/app/src/main/res/layout-land/cpp_app_keyboard.xml b/app/src/main/res/layout-land/cpp_app_keyboard.xml
index 0219fc2a..e735a01d 100644
--- a/app/src/main/res/layout-land/cpp_app_keyboard.xml
+++ b/app/src/main/res/layout-land/cpp_app_keyboard.xml
@@ -34,10 +34,10 @@
         a:baselineAligned="false"
         a:orientation="horizontal">
 
-        <include layout="@layout/cpp_app_button_vars" />
-
         <include layout="@layout/cpp_app_button_copy" />
 
+        <include layout="@layout/cpp_app_button_paste" />
+
         <include layout="@layout/cpp_app_button_7" />
 
         <include layout="@layout/cpp_app_button_8" />
@@ -48,7 +48,7 @@
 
         <include layout="@layout/cpp_app_button_division" />
 
-        <include layout="@layout/cpp_app_button_equals" />
+        <include layout="@layout/cpp_app_button_memory" />
 
     </LinearLayout>
 
@@ -59,9 +59,9 @@
         a:baselineAligned="false"
         a:orientation="horizontal">
 
-        <include layout="@layout/cpp_app_button_functions" />
+        <include layout="@layout/cpp_app_button_vars" />
 
-        <include layout="@layout/cpp_app_button_paste" />
+        <include layout="@layout/cpp_app_button_functions" />
 
         <include layout="@layout/cpp_app_button_4" />
 
@@ -84,9 +84,9 @@
         a:baselineAligned="false"
         a:orientation="horizontal">
 
-        <include layout="@layout/cpp_app_button_operators" />
+        <include layout="@layout/cpp_app_button_left" />
 
-        <include layout="@layout/cpp_app_button_donate" />
+        <include layout="@layout/cpp_app_button_right" />
 
         <include layout="@layout/cpp_app_button_1" />
 
diff --git a/app/src/main/res/layout/cpp_app_button_6.xml b/app/src/main/res/layout/cpp_app_button_6.xml
index de56b116..1abffd6e 100644
--- a/app/src/main/res/layout/cpp_app_button_6.xml
+++ b/app/src/main/res/layout/cpp_app_button_6.xml
@@ -29,5 +29,6 @@
     a:id="@id/cpp_button_6"
     style="?attr/cpp_button_style_digit"
     a:text="6"
+    c:directionTextUp="√"
     c:directionTextLeft="F"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_9.xml b/app/src/main/res/layout/cpp_app_button_9.xml
index dbca25a2..5dfa09b1 100644
--- a/app/src/main/res/layout/cpp_app_button_9.xml
+++ b/app/src/main/res/layout/cpp_app_button_9.xml
@@ -29,7 +29,5 @@
     a:id="@id/cpp_button_9"
     style="?attr/cpp_button_style_digit"
     a:text="9"
-    c:directionTextDown="e"
     c:directionTextLeft="0x:"
-    c:directionTextUp="π"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_clear.xml b/app/src/main/res/layout/cpp_app_button_clear.xml
index f274f6c8..179b4f44 100644
--- a/app/src/main/res/layout/cpp_app_button_clear.xml
+++ b/app/src/main/res/layout/cpp_app_button_clear.xml
@@ -22,9 +22,12 @@
   ~ Site:  http://se.solovyev.org
   -->
 
-<Button
+<org.solovyev.android.views.dragbutton.DirectionDragButton
     a:id="@id/cpp_button_clear"
     style="?attr/cpp_button_style_control_image"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:a="http://schemas.android.com/apk/res/android"
+    a:background="@color/grey_850"
     a:text="@string/c_clear"
+    app:directionTextUp="MC"
     a:textStyle="bold"/>
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_division.xml b/app/src/main/res/layout/cpp_app_button_division.xml
index 3a3cbf7a..fd92ccb8 100644
--- a/app/src/main/res/layout/cpp_app_button_division.xml
+++ b/app/src/main/res/layout/cpp_app_button_division.xml
@@ -29,6 +29,4 @@
     a:id="@id/cpp_button_division"
     style="?attr/cpp_button_style_operation"
     a:text="/"
-    c:directionTextDown="√"
-    c:directionTextUp="%"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_equals_no_bg.xml b/app/src/main/res/layout/cpp_app_button_equals_no_bg.xml
index dea94781..da06dcb8 100644
--- a/app/src/main/res/layout/cpp_app_button_equals_no_bg.xml
+++ b/app/src/main/res/layout/cpp_app_button_equals_no_bg.xml
@@ -29,8 +29,7 @@
     style="?attr/cpp_button_style_control"
     a:background="@drawable/button_no_bg"
     a:text="="
-    a:textColor="?android:attr/textColorPrimary"
-    c:directionTextColor="?android:attr/textColorPrimary"
+    a:textColor="?attr/cpp_text_color"
     c:directionTextDown="@string/cpp_plot_button_text"
     c:directionTextUp="≡"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_erase.xml b/app/src/main/res/layout/cpp_app_button_erase.xml
index 83d5f3ff..b3ed7b80 100644
--- a/app/src/main/res/layout/cpp_app_button_erase.xml
+++ b/app/src/main/res/layout/cpp_app_button_erase.xml
@@ -25,5 +25,6 @@
 <ImageButton
     xmlns:a="http://schemas.android.com/apk/res/android"
     a:id="@id/cpp_button_erase"
+    a:background="@color/cpp_material_light_darker"
     style="?attr/cpp_button_style_control_image"
     a:src="@drawable/ic_backspace_white_48dp" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_functions.xml b/app/src/main/res/layout/cpp_app_button_functions.xml
index 55a627b8..445d9c16 100644
--- a/app/src/main/res/layout/cpp_app_button_functions.xml
+++ b/app/src/main/res/layout/cpp_app_button_functions.xml
@@ -31,4 +31,5 @@
     a:text="@string/cpp_kb_functions"
     a:textStyle="italic"
     c:directionTextUp="+ƒ"
+    c:directionTextDown="+π"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_memory.xml b/app/src/main/res/layout/cpp_app_button_memory.xml
index edd46cb0..89ec2124 100644
--- a/app/src/main/res/layout/cpp_app_button_memory.xml
+++ b/app/src/main/res/layout/cpp_app_button_memory.xml
@@ -27,5 +27,5 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     a:text="@string/cpp_kb_memory_recall"
     app:directionTextDown="@string/cpp_kb_memory_minus"
-    app:directionTextLeft="@string/cpp_kb_memory_clear"
-    app:directionTextUp="@string/cpp_kb_memory_plus" />
\ No newline at end of file
+    app:directionTextUp="@string/cpp_kb_memory_plus"
+    a:textStyle="bold"/>
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_minus.xml b/app/src/main/res/layout/cpp_app_button_minus.xml
index 82b01935..5672279f 100644
--- a/app/src/main/res/layout/cpp_app_button_minus.xml
+++ b/app/src/main/res/layout/cpp_app_button_minus.xml
@@ -28,5 +28,4 @@
     a:id="@id/cpp_button_subtraction"
     style="?attr/cpp_button_style_operation"
     a:text="−"
-    c:directionTextDown="@string/cpp_kb_operators"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_multiplication.xml b/app/src/main/res/layout/cpp_app_button_multiplication.xml
index bf1f979a..d95c233f 100644
--- a/app/src/main/res/layout/cpp_app_button_multiplication.xml
+++ b/app/src/main/res/layout/cpp_app_button_multiplication.xml
@@ -29,7 +29,4 @@
     a:id="@id/cpp_button_multiplication"
     style="?attr/cpp_button_style_operation"
     a:text="×"
-    c:directionTextDown="^2"
-    c:directionTextLeft="Π"
-    c:directionTextUp="^"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_percent.xml b/app/src/main/res/layout/cpp_app_button_percent.xml
new file mode 100644
index 00000000..842c63ad
--- /dev/null
+++ b/app/src/main/res/layout/cpp_app_button_percent.xml
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  ~ Copyright 2013 serso aka se.solovyev
+  ~
+  ~ 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.
+  ~
+  ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  ~ Contact details
+  ~
+  ~ Email: se.solovyev@gmail.com
+  ~ Site:  http://se.solovyev.org
+  -->
+
+<org.solovyev.android.views.dragbutton.DirectionDragButton
+    a:id="@id/cpp_button_percent"
+    style="?attr/cpp_button_style_digit"
+    xmlns:a="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    a:text="%"
+    app:directionTextDown="^2"
+    app:directionTextUp="^"
+    tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_round_brackets.xml b/app/src/main/res/layout/cpp_app_button_round_brackets.xml
index 529f869d..06dac7c6 100644
--- a/app/src/main/res/layout/cpp_app_button_round_brackets.xml
+++ b/app/src/main/res/layout/cpp_app_button_round_brackets.xml
@@ -30,6 +30,6 @@
     style="?attr/cpp_button_style_digit"
     a:text="( )"
     c:directionTextDown=")"
-    c:directionTextLeft="(.)"
+    c:directionTextLeft="(…)"
     c:directionTextUp="("
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_button_vars.xml b/app/src/main/res/layout/cpp_app_button_vars.xml
index e19075d1..bf077783 100644
--- a/app/src/main/res/layout/cpp_app_button_vars.xml
+++ b/app/src/main/res/layout/cpp_app_button_vars.xml
@@ -30,5 +30,6 @@
     style="?attr/cpp_button_style_control"
     a:text="@string/cpp_kb_variables"
     a:textStyle="italic"
-    c:directionTextUp="+π"
+    c:directionTextDown="e"
+    c:directionTextUp="π"
     tools:ignore="HardcodedText" />
\ No newline at end of file
diff --git a/app/src/main/res/layout/cpp_app_keyboard.xml b/app/src/main/res/layout/cpp_app_keyboard.xml
index fa3079a7..24d264ce 100644
--- a/app/src/main/res/layout/cpp_app_keyboard.xml
+++ b/app/src/main/res/layout/cpp_app_keyboard.xml
@@ -27,6 +27,23 @@
     a:layout_height="match_parent"
     a:orientation="vertical">
 
+    <LinearLayout
+        a:layout_width="match_parent"
+        a:layout_height="0dp"
+        a:layout_weight="1">
+
+        <include layout="@layout/cpp_app_button_vars" />
+
+        <include layout="@layout/cpp_app_button_functions" />
+
+        <include layout="@layout/cpp_app_button_percent" />
+
+        <include layout="@layout/cpp_app_button_erase" />
+
+        <include layout="@layout/cpp_app_button_clear" />
+
+    </LinearLayout>
+
     <LinearLayout
         a:layout_width="match_parent"
         a:layout_height="0dp"
@@ -38,9 +55,10 @@
 
         <include layout="@layout/cpp_app_button_9" />
 
-        <include layout="@layout/cpp_app_button_multiplication" />
+        <include layout="@layout/cpp_app_button_division" />
+
+        <include layout="@layout/cpp_app_button_memory" />
 
-        <include layout="@layout/cpp_app_button_clear" />
 
     </LinearLayout>
 
@@ -55,9 +73,9 @@
 
         <include layout="@layout/cpp_app_button_6" />
 
-        <include layout="@layout/cpp_app_button_division" />
+        <include layout="@layout/cpp_app_button_multiplication" />
 
-        <include layout="@layout/cpp_app_button_erase" />
+        <include layout="@layout/cpp_app_button_copy" />
 
     </LinearLayout>
 
@@ -72,23 +90,6 @@
 
         <include layout="@layout/cpp_app_button_3" />
 
-        <include layout="@layout/cpp_app_button_plus" />
-
-        <include layout="@layout/cpp_app_button_copy" />
-
-    </LinearLayout>
-
-    <LinearLayout
-        a:layout_width="match_parent"
-        a:layout_height="0dp"
-        a:layout_weight="1">
-
-        <include layout="@layout/cpp_app_button_round_brackets" />
-
-        <include layout="@layout/cpp_app_button_0" />
-
-        <include layout="@layout/cpp_app_button_dot" />
-
         <include layout="@layout/cpp_app_button_minus" />
 
         <include layout="@layout/cpp_app_button_paste" />
@@ -101,13 +102,13 @@
         a:layout_height="0dp"
         a:layout_weight="1">
 
-        <include layout="@layout/cpp_app_button_left" />
+        <include layout="@layout/cpp_app_button_round_brackets" />
 
-        <include layout="@layout/cpp_app_button_right" />
+        <include layout="@layout/cpp_app_button_0" />
 
-        <include layout="@layout/cpp_app_button_vars" />
+        <include layout="@layout/cpp_app_button_dot" />
 
-        <include layout="@layout/cpp_app_button_functions" />
+        <include layout="@layout/cpp_app_button_plus" />
 
         <include layout="@layout/cpp_app_button_history" />
 
diff --git a/app/src/main/res/values-land/dimens.xml b/app/src/main/res/values-land/dimens.xml
new file mode 100644
index 00000000..f9e13923
--- /dev/null
+++ b/app/src/main/res/values-land/dimens.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <item name="cpp_direction_text_scale" format="float" type="dimen">0.45</item>
+    <item name="cpp_direction_text_scale_units" format="float" type="dimen">0.45</item>
+</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/colors.xml b/app/src/main/res/values/colors.xml
index 064b58e2..cecafb02 100644
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -60,5 +60,6 @@
     <color name="grey_900">#212121</color>
     <color name="grey_950">#101010</color>
     <color name="grey_800">#424242</color>
+    <color name="grey_850">#313131</color>
 
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/dimens.xml b/app/src/main/res/values/dimens.xml
index 2f979705..47cc6598 100644
--- a/app/src/main/res/values/dimens.xml
+++ b/app/src/main/res/values/dimens.xml
@@ -10,8 +10,8 @@
     <dimen name="cpp_button_padding">1px</dimen>
     <dimen name="cpp_direction_text_default_padding">2dp</dimen>
     <dimen name="cpp_direction_text_min_size">9dp</dimen>
-    <item name="cpp_direction_text_scale" format="float" type="dimen">0.45</item>
-    <item name="cpp_direction_text_scale_units" format="float" type="dimen">0.35</item>
+    <item name="cpp_direction_text_scale" format="float" type="dimen">0.35</item>
+    <item name="cpp_direction_text_scale_units" format="float" type="dimen">0.3</item>
     <dimen name="cpp_button_corner">1dp</dimen>
 
     <dimen name="cpp_keyboard_button_direction_text_padding">4dp</dimen>
diff --git a/app/src/main/res/values/text_non_translatable.xml b/app/src/main/res/values/text_non_translatable.xml
index c835e01b..0b3968b6 100644
--- a/app/src/main/res/values/text_non_translatable.xml
+++ b/app/src/main/res/values/text_non_translatable.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <string name="cpp_kb_variables" translatable="false">π</string>
+    <string name="cpp_kb_variables" translatable="false">π…</string>
     <string name="cpp_kb_functions" translatable="false">ƒ</string>
     <string name="cpp_kb_operators" translatable="false">∂</string>
     <string name="cpp_kb_undo" translatable="false">↶</string>
diff --git a/app/src/main/res/xml/preferences_appearance.xml b/app/src/main/res/xml/preferences_appearance.xml
index 2834ff59..ac7602ad 100644
--- a/app/src/main/res/xml/preferences_appearance.xml
+++ b/app/src/main/res/xml/preferences_appearance.xml
@@ -64,13 +64,6 @@
         a:key="autoOrientation"
         a:title="@string/cpp_prefs_auto_rotate_screen" />
 
-
-    <android.preference.CheckBoxPreference
-        a:defaultValue="true"
-        a:key="showEqualsButton"
-        a:summary="@string/c_show_equals_button_summary"
-        a:title="@string/c_show_equals_button_title" />
-
     <android.preference.CheckBoxPreference
         a:key="gui.keepScreenOn"
         a:title="@string/cpp_prefs_keep_screen_on" />