diff --git a/calculatorpp/pom.xml b/calculatorpp/pom.xml
index 5fa5f331..b90fa62c 100644
--- a/calculatorpp/pom.xml
+++ b/calculatorpp/pom.xml
@@ -1,340 +1,340 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-
-    <parent>
-        <groupId>org.solovyev.android</groupId>
-        <artifactId>calculatorpp-parent</artifactId>
-        <version>1.3.2</version>
-    </parent>
-
-    <modelVersion>4.0.0</modelVersion>
-
-    <groupId>org.solovyev.android</groupId>
-    <artifactId>calculatorpp</artifactId>
-    <packaging>apk</packaging>
-    <name>Calculator++ Application</name>
-
-    <dependencies>
-
-        <!-- OWN -->
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>calculatorpp-core</artifactId>
-            <version>1.3.2</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev</groupId>
-            <artifactId>common-core</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev</groupId>
-            <artifactId>common-text</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-core</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-ads</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-view</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-preferences</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-other</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-menu</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>android-common-sherlock</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-
-        <dependency>
-            <groupId>org.solovyev</groupId>
-            <artifactId>jscl</artifactId>
-        </dependency>
-
-        <!--OTHER-->
-        <dependency>
-            <groupId>ch.acra</groupId>
-            <artifactId>acra</artifactId>
-            <version>4.3.0</version>
-        </dependency>
-
-        <dependency>
-            <groupId>com.google.android</groupId>
-            <artifactId>android</artifactId>
-            <scope>provided</scope>
-        </dependency>
-
-        <dependency>
-            <groupId>com.google.android</groupId>
-            <artifactId>support-v4</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>com.actionbarsherlock</groupId>
-            <artifactId>library</artifactId>
-            <type>apklib</type>
-        </dependency>
-
-        <dependency>
-            <groupId>net.sf.opencsv</groupId>
-            <artifactId>opencsv</artifactId>
-            <version>2.0</version>
-            <scope>test</scope>
-        </dependency>
-
-        <dependency>
-            <groupId>org.simpleframework</groupId>
-            <artifactId>simple-xml</artifactId>
-        </dependency>
-
-        <dependency>
-            <groupId>achartengine</groupId>
-            <artifactId>achartengine</artifactId>
-            <version>0.7.0</version>
-        </dependency>
-
-        <dependency>
-            <groupId>admob</groupId>
-            <artifactId>admob</artifactId>
-            <version>6.1.0</version>
-        </dependency>
-
-        <dependency>
-            <groupId>org.solovyev.android</groupId>
-            <artifactId>billing</artifactId>
-            <version>0.1</version>
-            <!--<type>apklib</type>-->
-        </dependency>
-
-        <dependency>
-            <groupId>com.google.guava</groupId>
-            <artifactId>guava</artifactId>
-            <version>11.0.2</version>
-        </dependency>
-
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <scope>test</scope>
-        </dependency>
-
-        <dependency>
-            <groupId>com.intellij</groupId>
-            <artifactId>annotations</artifactId>
-        </dependency>
-
-    </dependencies>
-
-    <build>
-
-
-        <plugins>
-
-            <plugin>
-                <groupId>com.jayway.maven.plugins.android.generation2</groupId>
-                <artifactId>android-maven-plugin</artifactId>
-                <extensions>true</extensions>
-                <configuration>
-                    <manifest>
-                        <debuggable>true</debuggable>
-                    </manifest>
-                </configuration>
-                <executions>
-                    <execution>
-                        <id>manifestUpdate</id>
-                        <phase>process-resources</phase>
-                        <goals>
-                            <goal>manifest-update</goal>
-                        </goals>
-                    </execution>
-                    <execution>
-                        <id>alignApk</id>
-                        <phase>package</phase>
-                        <goals>
-                            <goal>zipalign</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-
-        </plugins>
-
-    </build>
-
-    <profiles>
-
-        <profile>
-            <id>release</id>
-            <!-- via this activation the profile is automatically used when the release is done with the maven release
-            plugin -->
-            <activation>
-                <property>
-                    <name>performRelease</name>
-                    <value>true</value>
-                </property>
-            </activation>
-
-            <build>
-                <plugins>
-
-                    <plugin>
-                        <groupId>org.codehaus.mojo</groupId>
-                        <artifactId>properties-maven-plugin</artifactId>
-                        <version>1.0-alpha-2</version>
-                        <executions>
-                            <execution>
-                                <phase>initialize</phase>
-                                <goals>
-                                    <goal>read-project-properties</goal>
-                                </goals>
-                                <configuration>
-                                    <files>
-                                        <file>${project.basedir}/misc/env/jarsigner.properties</file>
-                                    </files>
-                                </configuration>
-                            </execution>
-                        </executions>
-                    </plugin>
-
-                    <plugin>
-                        <groupId>org.apache.maven.plugins</groupId>
-                        <artifactId>maven-jarsigner-plugin</artifactId>
-                        <executions>
-                            <execution>
-                                <id>signing</id>
-                                <goals>
-                                    <goal>sign</goal>
-                                    <goal>verify</goal>
-                                </goals>
-                                <phase>package</phase>
-                                <inherited>true</inherited>
-                                <configuration>
-                                    <removeExistingSignatures>true</removeExistingSignatures>
-                                    <archiveDirectory/>
-                                    <includes>
-                                        <include>${project.build.directory}/${project.artifactId}-${project.version}.apk</include>
-                                    </includes>
-                                    <keystore>${sign.keystore}</keystore>
-                                    <alias>${sign.alias}</alias>
-                                    <storepass>${sign.storepass}</storepass>
-                                    <keypass>${sign.keypass}</keypass>
-                                    <verbose>false</verbose>
-                                </configuration>
-                            </execution>
-                        </executions>
-                    </plugin>
-
-                    <!-- the signed apk then needs to be zipaligned and we activate proguard and we run the manifest
-                    update -->
-                    <plugin>
-                        <groupId>com.jayway.maven.plugins.android.generation2</groupId>
-                        <artifactId>android-maven-plugin</artifactId>
-                        <inherited>true</inherited>
-                        <configuration>
-
-                            <sign>
-                                <debug>false</debug>
-                            </sign>
-
-                            <zipalign>
-                                <verbose>false</verbose>
-                                <inputApk>${project.build.directory}/${project.artifactId}-${project.version}.apk</inputApk>
-                                <outputApk>${project.build.directory}/${project.artifactId}-${project.version}-signed-aligned.apk</outputApk>
-                            </zipalign>
-
-                            <manifest>
-                                <debuggable>false</debuggable>
-                                <versionCodeAutoIncrement>true</versionCodeAutoIncrement>
-                            </manifest>
-
-                            <proguard>
-                                <skip>true</skip>
-                            </proguard>
-                        </configuration>
-
-                        <executions>
-                            <execution>
-                                <id>manifestUpdate</id>
-                                <phase>process-resources</phase>
-                                <goals>
-                                    <goal>manifest-update</goal>
-                                </goals>
-                            </execution>
-                            <execution>
-                                <id>alignApk</id>
-                                <phase>package</phase>
-                                <goals>
-                                    <goal>zipalign</goal>
-                                </goals>
-                            </execution>
-                        </executions>
-                    </plugin>
-
-                    <plugin>
-                        <groupId>org.codehaus.mojo</groupId>
-                        <artifactId>build-helper-maven-plugin</artifactId>
-                        <configuration>
-                            <artifacts>
-                                <artifact>
-                                    <file>${project.build.directory}/${project.artifactId}-${project.version}-signed-aligned.apk</file>
-                                    <type>apk</type>
-                                    <classifier>signed-aligned</classifier>
-                                </artifact>
-                                <artifact>
-                                    <file>${project.build.directory}/proguard/mapping.txt</file>
-                                    <type>map</type>
-                                    <classifier>release</classifier>
-                                </artifact>
-                            </artifacts>
-                        </configuration>
-                        <executions>
-                            <execution>
-                                <id>attach-signed-aligned</id>
-                                <phase>package</phase>
-                                <goals>
-                                    <goal>attach-artifact</goal>
-                                </goals>
-                            </execution>
-                        </executions>
-                    </plugin>
-
-                </plugins>
-            </build>
-        </profile>
-    </profiles>
-
-
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>org.solovyev.android</groupId>
+        <artifactId>calculatorpp-parent</artifactId>
+        <version>1.3.2</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.solovyev.android</groupId>
+    <artifactId>calculatorpp</artifactId>
+    <packaging>apk</packaging>
+    <name>Calculator++ Application</name>
+
+    <dependencies>
+
+        <!-- OWN -->
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>calculatorpp-core</artifactId>
+            <version>1.3.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev</groupId>
+            <artifactId>common-core</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev</groupId>
+            <artifactId>common-text</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-core</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-ads</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-view</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-preferences</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-other</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-menu</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>android-common-sherlock</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+
+        <dependency>
+            <groupId>org.solovyev</groupId>
+            <artifactId>jscl</artifactId>
+        </dependency>
+
+        <!--OTHER-->
+        <dependency>
+            <groupId>ch.acra</groupId>
+            <artifactId>acra</artifactId>
+            <version>4.3.0</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.android</groupId>
+            <artifactId>android</artifactId>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.android</groupId>
+            <artifactId>support-v4</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>com.actionbarsherlock</groupId>
+            <artifactId>library</artifactId>
+            <type>apklib</type>
+        </dependency>
+
+        <dependency>
+            <groupId>net.sf.opencsv</groupId>
+            <artifactId>opencsv</artifactId>
+            <version>2.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.simpleframework</groupId>
+            <artifactId>simple-xml</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>achartengine</groupId>
+            <artifactId>achartengine</artifactId>
+            <version>0.7.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>admob</groupId>
+            <artifactId>admob</artifactId>
+            <version>6.1.0</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.solovyev.android</groupId>
+            <artifactId>billing</artifactId>
+            <version>0.1</version>
+            <!--<type>apklib</type>-->
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>11.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.intellij</groupId>
+            <artifactId>annotations</artifactId>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+
+
+        <plugins>
+
+            <plugin>
+                <groupId>com.jayway.maven.plugins.android.generation2</groupId>
+                <artifactId>android-maven-plugin</artifactId>
+                <extensions>true</extensions>
+                <configuration>
+                    <manifest>
+                        <debuggable>true</debuggable>
+                    </manifest>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>manifestUpdate</id>
+                        <phase>process-resources</phase>
+                        <goals>
+                            <goal>manifest-update</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>alignApk</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>zipalign</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+
+        </plugins>
+
+    </build>
+
+    <profiles>
+
+        <profile>
+            <id>release</id>
+            <!-- via this activation the profile is automatically used when the release is done with the maven release
+            plugin -->
+            <activation>
+                <property>
+                    <name>performRelease</name>
+                    <value>true</value>
+                </property>
+            </activation>
+
+            <build>
+                <plugins>
+
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>properties-maven-plugin</artifactId>
+                        <version>1.0-alpha-2</version>
+                        <executions>
+                            <execution>
+                                <phase>initialize</phase>
+                                <goals>
+                                    <goal>read-project-properties</goal>
+                                </goals>
+                                <configuration>
+                                    <files>
+                                        <file>${project.basedir}/misc/env/jarsigner.properties</file>
+                                    </files>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-jarsigner-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <id>signing</id>
+                                <goals>
+                                    <goal>sign</goal>
+                                    <goal>verify</goal>
+                                </goals>
+                                <phase>package</phase>
+                                <inherited>true</inherited>
+                                <configuration>
+                                    <removeExistingSignatures>true</removeExistingSignatures>
+                                    <archiveDirectory/>
+                                    <includes>
+                                        <include>${project.build.directory}/${project.artifactId}-${project.version}.apk</include>
+                                    </includes>
+                                    <keystore>${sign.keystore}</keystore>
+                                    <alias>${sign.alias}</alias>
+                                    <storepass>${sign.storepass}</storepass>
+                                    <keypass>${sign.keypass}</keypass>
+                                    <verbose>false</verbose>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+
+                    <!-- the signed apk then needs to be zipaligned and we activate proguard and we run the manifest
+                    update -->
+                    <plugin>
+                        <groupId>com.jayway.maven.plugins.android.generation2</groupId>
+                        <artifactId>android-maven-plugin</artifactId>
+                        <inherited>true</inherited>
+                        <configuration>
+
+                            <sign>
+                                <debug>false</debug>
+                            </sign>
+
+                            <zipalign>
+                                <verbose>false</verbose>
+                                <inputApk>${project.build.directory}/${project.artifactId}-${project.version}.apk</inputApk>
+                                <outputApk>${project.build.directory}/${project.artifactId}-${project.version}-signed-aligned.apk</outputApk>
+                            </zipalign>
+
+                            <manifest>
+                                <debuggable>false</debuggable>
+                                <versionCodeAutoIncrement>true</versionCodeAutoIncrement>
+                            </manifest>
+
+                            <proguard>
+                                <skip>true</skip>
+                            </proguard>
+                        </configuration>
+
+                        <executions>
+                            <execution>
+                                <id>manifestUpdate</id>
+                                <phase>process-resources</phase>
+                                <goals>
+                                    <goal>manifest-update</goal>
+                                </goals>
+                            </execution>
+                            <execution>
+                                <id>alignApk</id>
+                                <phase>package</phase>
+                                <goals>
+                                    <goal>zipalign</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
+
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>build-helper-maven-plugin</artifactId>
+                        <configuration>
+                            <artifacts>
+                                <artifact>
+                                    <file>${project.build.directory}/${project.artifactId}-${project.version}-signed-aligned.apk</file>
+                                    <type>apk</type>
+                                    <classifier>signed-aligned</classifier>
+                                </artifact>
+                                <artifact>
+                                    <file>${project.build.directory}/proguard/mapping.txt</file>
+                                    <type>map</type>
+                                    <classifier>release</classifier>
+                                </artifact>
+                            </artifacts>
+                        </configuration>
+                        <executions>
+                            <execution>
+                                <id>attach-signed-aligned</id>
+                                <phase>package</phase>
+                                <goals>
+                                    <goal>attach-artifact</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
+
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+
 </project>
\ No newline at end of file
diff --git a/calculatorpp/res/drawable-xlarge-hdpi/kb_copy.png b/calculatorpp/res/drawable-xlarge-hdpi/kb_copy.png
new file mode 100644
index 00000000..44c24296
Binary files /dev/null and b/calculatorpp/res/drawable-xlarge-hdpi/kb_copy.png differ
diff --git a/calculatorpp/res/drawable-xlarge-hdpi/kb_delete.png b/calculatorpp/res/drawable-xlarge-hdpi/kb_delete.png
new file mode 100644
index 00000000..f5ca50ec
Binary files /dev/null and b/calculatorpp/res/drawable-xlarge-hdpi/kb_delete.png differ
diff --git a/calculatorpp/res/drawable-xlarge-hdpi/kb_heart.png b/calculatorpp/res/drawable-xlarge-hdpi/kb_heart.png
new file mode 100644
index 00000000..97139f4b
Binary files /dev/null and b/calculatorpp/res/drawable-xlarge-hdpi/kb_heart.png differ
diff --git a/calculatorpp/res/drawable-xlarge-hdpi/kb_paste.png b/calculatorpp/res/drawable-xlarge-hdpi/kb_paste.png
new file mode 100644
index 00000000..da55e7a3
Binary files /dev/null and b/calculatorpp/res/drawable-xlarge-hdpi/kb_paste.png differ
diff --git a/calculatorpp/res/drawable/metro_button_light_shape.xml b/calculatorpp/res/drawable/metro_button_light_shape.xml
index 0a291ba1..b0b8e3a7 100644
--- a/calculatorpp/res/drawable/metro_button_light_shape.xml
+++ b/calculatorpp/res/drawable/metro_button_light_shape.xml
@@ -15,6 +15,6 @@
 -->
 
 <shape xmlns:android="http://schemas.android.com/apk/res/android">
-    <solid android:color="#393939"/>
+    <solid android:color="@color/metro_light_button_background"/>
     <corners android:radius="1dp" />
 </shape>
diff --git a/calculatorpp/res/values-large/dimens.xml b/calculatorpp/res/values-large/dimens.xml
index 642d5abd..8a3e9ae0 100644
--- a/calculatorpp/res/values-large/dimens.xml
+++ b/calculatorpp/res/values-large/dimens.xml
@@ -1,5 +1,7 @@
 <resources>
     <dimen name="fragment_text_size">10sp</dimen>
+    <dimen name="fragment_title_text_size">20sp</dimen>
+
     <dimen name="editor_text_size">15sp</dimen>
     <dimen name="display_text_size">15sp</dimen>
     <dimen name="keyboard_button_text_size">20dp</dimen>
diff --git a/calculatorpp/res/values-xlarge/dimens.xml b/calculatorpp/res/values-xlarge/dimens.xml
new file mode 100644
index 00000000..4a3f9a7c
--- /dev/null
+++ b/calculatorpp/res/values-xlarge/dimens.xml
@@ -0,0 +1,9 @@
+<resources>
+    <dimen name="fragment_text_size">20sp</dimen>
+    <dimen name="fragment_title_text_size">30sp</dimen>
+    <dimen name="editor_text_size">30sp</dimen>
+    <dimen name="display_text_size">30sp</dimen>
+    <dimen name="keyboard_button_text_size">40dp</dimen>
+    <dimen name="math_entity_text_size">30sp</dimen>
+    <dimen name="math_entity_description_text_size">20sp</dimen>
+</resources>
\ No newline at end of file
diff --git a/calculatorpp/res/values/colors.xml b/calculatorpp/res/values/colors.xml
index 9726fba0..b75bba76 100644
--- a/calculatorpp/res/values/colors.xml
+++ b/calculatorpp/res/values/colors.xml
@@ -18,4 +18,5 @@
     <color name="metro_blue_color">#10648c</color>
     <color name="metro_green_color">#088e3a</color>
     <color name="metro_purple_color">#651456</color>
+    <color name="metro_light_button_background">#393939</color>
 </resources>
\ No newline at end of file
diff --git a/calculatorpp/res/values/dimens.xml b/calculatorpp/res/values/dimens.xml
index 6e5dddaf..53bd110a 100644
--- a/calculatorpp/res/values/dimens.xml
+++ b/calculatorpp/res/values/dimens.xml
@@ -1,7 +1,10 @@
 <resources>
     <dimen name="button_margin">0.5dp</dimen>
     <dimen name="text_size">20sp</dimen>
+
     <dimen name="fragment_text_size">15sp</dimen>
+    <dimen name="fragment_title_text_size">20sp</dimen>
+
     <dimen name="keyboard_button_text_size">30dp</dimen>
     <dimen name="button_text_size">20dp</dimen>
     <dimen name="display_text_size">25sp</dimen>
diff --git a/calculatorpp/res/values/theme_default.xml b/calculatorpp/res/values/theme_default.xml
index 8ddc41f3..32455bf3 100644
--- a/calculatorpp/res/values/theme_default.xml
+++ b/calculatorpp/res/values/theme_default.xml
@@ -37,7 +37,7 @@
 
     <style name="default_fragment_title_style">
         <item name="android:textColor">@android:color/white</item>
-        <item name="android:textSize">20sp</item>
+        <item name="android:textSize">@dimen/fragment_title_text_size</item>
     </style>
 
     <style name="default_button_style" parent="button_style">
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/CalculatorPlotFragment.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/CalculatorPlotFragment.java
index 4634db5e..7ca52fc8 100644
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/CalculatorPlotFragment.java
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/CalculatorPlotFragment.java
@@ -171,6 +171,8 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
 
             //noinspection ConstantConditions
             this.chart = PlotUtils.prepareChart(getMinValue(null), getMaxValue(null), preparedInput.getExpression(), preparedInput.getVariable(), bgColor, interpolate, realLineColor.getColor(), imagLineColor.getColor());
+        } else {
+            this.chart = null;
         }
     }
 
@@ -203,6 +205,12 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
     }
 
     private void createGraphicalView(@NotNull View root, @Nullable PlotBoundaries plotBoundaries) {
+        final ViewGroup graphContainer = (ViewGroup) root.findViewById(R.id.main_fragment_layout);
+
+        if (graphicalView != null) {
+            graphContainer.removeView(graphicalView);
+        }
+
         if (!preparedInput.isError()) {
             final XYChart chart = this.chart;
             assert chart != null;
@@ -210,12 +218,6 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
             double minValue = getMinValue(plotBoundaries);
             double maxValue = getMaxValue(plotBoundaries);
 
-            final ViewGroup graphContainer = (ViewGroup) root.findViewById(R.id.main_fragment_layout);
-
-            if (graphicalView != null) {
-                graphContainer.removeView(graphicalView);
-            }
-
             // reverting boundaries (as in prepareChart() we add some cached values )
             double minX = Double.MAX_VALUE;
             double minY = Double.MAX_VALUE;
@@ -260,7 +262,6 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
             graphicalView.addPanListener(new PanListener() {
                 @Override
                 public void panApplied() {
-                    Log.d(TAG, "org.achartengine.tools.PanListener.panApplied");
                     updateDataSets(chart);
                 }
 
@@ -269,7 +270,7 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
 
             updateDataSets(chart, 50);
         } else {
-            Toast.makeText(this.getActivity(), "Plot is not possible!", Toast.LENGTH_LONG).show();
+            graphicalView = null;
         }
 
     }
@@ -294,56 +295,54 @@ public class CalculatorPlotFragment extends CalculatorFragment implements Calcul
         final Generic expression = preparedInput.getExpression();
         final Constant variable = preparedInput.getVariable();
 
-        pendingOperation.setObject(new Runnable() {
-            @Override
-            public void run() {
-                // allow only one runner at one time
-                synchronized (pendingOperation) {
-                    //lock all operations with history
-                    if (pendingOperation.getObject() == this) {
+        if (expression != null && variable != null) {
+            pendingOperation.setObject(new Runnable() {
+                @Override
+                public void run() {
+                    // allow only one runner at one time
+                    synchronized (pendingOperation) {
+                        //lock all operations with history
+                        if (pendingOperation.getObject() == this) {
 
-                        plotExecutor.execute(new Runnable() {
-                            @Override
-                            public void run() {
-                                Log.d(TAG, "org.solovyev.android.calculator.plot.CalculatorPlotActivity.updateDataSets");
+                            plotExecutor.execute(new Runnable() {
+                                @Override
+                                public void run() {
+                                    final XYMultipleSeriesRenderer dr = chart.getRenderer();
 
-                                final XYMultipleSeriesRenderer dr = chart.getRenderer();
+                                    final MyXYSeries realSeries = (MyXYSeries) chart.getDataset().getSeriesAt(0);
 
-                                //Log.d(CalculatorPlotActivity.class.getName(), "x = [" + dr.getXAxisMin() + ", " + dr.getXAxisMax() + "], y = [" + dr.getYAxisMin() + ", " + dr.getYAxisMax() + "]");
+                                    final MyXYSeries imagSeries;
+                                    if (chart.getDataset().getSeriesCount() > 1) {
+                                        imagSeries = (MyXYSeries) chart.getDataset().getSeriesAt(1);
+                                    } else {
+                                        imagSeries = new MyXYSeries(PlotUtils.getImagFunctionName(variable), PlotUtils.DEFAULT_NUMBER_OF_STEPS * 2);
+                                    }
 
-                                final MyXYSeries realSeries = (MyXYSeries) chart.getDataset().getSeriesAt(0);
-
-                                final MyXYSeries imagSeries;
-                                if (chart.getDataset().getSeriesCount() > 1) {
-                                    imagSeries = (MyXYSeries) chart.getDataset().getSeriesAt(1);
-                                } else {
-                                    imagSeries = new MyXYSeries(PlotUtils.getImagFunctionName(variable), PlotUtils.DEFAULT_NUMBER_OF_STEPS * 2);
-                                }
-
-                                try {
-                                    if (PlotUtils.addXY(dr.getXAxisMin(), dr.getXAxisMax(), expression, variable, realSeries, imagSeries, true, PlotUtils.DEFAULT_NUMBER_OF_STEPS)) {
-                                        if (chart.getDataset().getSeriesCount() <= 1) {
-                                            chart.getDataset().addSeries(imagSeries);
-                                            chart.getRenderer().addSeriesRenderer(PlotUtils.createImagRenderer(imagLineColor.getColor()));
+                                    try {
+                                        if (PlotUtils.addXY(dr.getXAxisMin(), dr.getXAxisMax(), expression, variable, realSeries, imagSeries, true, PlotUtils.DEFAULT_NUMBER_OF_STEPS)) {
+                                            if (chart.getDataset().getSeriesCount() <= 1) {
+                                                chart.getDataset().addSeries(imagSeries);
+                                                chart.getRenderer().addSeriesRenderer(PlotUtils.createImagRenderer(imagLineColor.getColor()));
+                                            }
                                         }
+                                    } catch (ArithmeticException e) {
+                                        // todo serso: translate
+                                        Toast.makeText(CalculatorPlotFragment.this.getActivity(), "Arithmetic error: " + e.getLocalizedMessage(), Toast.LENGTH_LONG).show();
                                     }
-                                } catch (ArithmeticException e) {
-                                    // todo serso: translate
-                                    Toast.makeText(CalculatorPlotFragment.this.getActivity(), "Arithmetic error: " + e.getLocalizedMessage(), Toast.LENGTH_LONG).show();
-                                }
 
-                                uiHandler.post(new Runnable() {
-                                    @Override
-                                    public void run() {
-                                        graphicalView.repaint();
-                                    }
-                                });
-                            }
-                        });
+                                    uiHandler.post(new Runnable() {
+                                        @Override
+                                        public void run() {
+                                            graphicalView.repaint();
+                                        }
+                                    });
+                                }
+                            });
+                        }
                     }
                 }
-            }
-        });
+            });
+        }
 
 
         uiHandler.postDelayed(pendingOperation.getObject(), millisToWait);
diff --git a/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/MyXYSeries.java b/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/MyXYSeries.java
index 42ba9e29..30f4145a 100644
--- a/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/MyXYSeries.java
+++ b/calculatorpp/src/main/java/org/solovyev/android/calculator/plot/MyXYSeries.java
@@ -9,8 +9,7 @@ package org.solovyev.android.calculator.plot;
 import org.achartengine.model.XYSeries;
 import org.achartengine.util.MathHelper;
 
-import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 
 /**
  * User: serso