diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index b56cfc8..360d67d 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -16,14 +16,9 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="e373569e-ee9b-4412-b2d3-a86c151abae2" name="Default" comment="">
-      <change beforePath="$PROJECT_DIR$/.idea/libraries/Gradle__net_studymongolian_mongol_library_1_16_6.xml" beforeDir="false" />
-      <change beforePath="$PROJECT_DIR$/.idea/misc.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/misc.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/Chimee.iml" beforeDir="false" afterPath="$PROJECT_DIR$/Chimee.iml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/app/app.iml" beforeDir="false" afterPath="$PROJECT_DIR$/app/app.iml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/app/build.gradle" beforeDir="false" afterPath="$PROJECT_DIR$/app/build.gradle" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/app/release/app-release.apk" beforeDir="false" afterPath="$PROJECT_DIR$/app/release/app-release.apk" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/OverlayTextView.java" beforeDir="false" afterPath="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/OverlayTextView.java" afterDir="false" />
     </list>
     <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
     <option name="TRACKING_ENABLED" value="true" />
@@ -49,8 +44,17 @@
       <file leaf-file-name="build.gradle" pinned="false" current-in-tab="true">
         <entry file="file://$PROJECT_DIR$/app/build.gradle">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="285">
-              <caret line="19" column="1" selection-start-line="19" selection-start-column="1" selection-end-line="19" selection-end-column="1" />
+            <state relative-caret-position="435">
+              <caret line="29" selection-start-line="29" selection-end-line="29" />
+            </state>
+          </provider>
+        </entry>
+      </file>
+      <file leaf-file-name="strings.xml" pinned="false" current-in-tab="false">
+        <entry file="file://$PROJECT_DIR$/app/src/main/res/values/strings.xml">
+          <provider selected="true" editor-type-id="text-editor">
+            <state relative-caret-position="275">
+              <caret line="62" column="22" selection-start-line="62" selection-start-column="22" selection-end-line="62" selection-end-column="22" />
             </state>
           </provider>
         </entry>
@@ -97,14 +101,8 @@
       <file leaf-file-name="TextView.java" pinned="false" current-in-tab="false">
         <entry file="file://$USER_HOME$/Library/Android/sdk/sources/android-28/android/widget/TextView.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="115725">
+            <state relative-caret-position="121050">
               <caret line="8070" column="16" selection-start-line="8070" selection-start-column="16" selection-end-line="8070" selection-end-column="16" />
-              <folding>
-                <element signature="e#202490#202491#0" expanded="true" />
-                <element signature="e#202525#202526#0" expanded="true" />
-                <element signature="e#202881#202882#0" expanded="true" />
-                <element signature="e#202915#202916#0" expanded="true" />
-              </folding>
             </state>
           </provider>
         </entry>
@@ -125,7 +123,7 @@
       <file leaf-file-name="Layout.java" pinned="false" current-in-tab="false">
         <entry file="file://$USER_HOME$/Library/Android/sdk/sources/android-28/android/text/Layout.java">
           <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="3960">
+            <state relative-caret-position="3435">
               <caret line="264" column="20" selection-start-line="264" selection-start-column="8" selection-end-line="264" selection-end-column="20" />
             </state>
           </provider>
@@ -140,15 +138,6 @@
           </provider>
         </entry>
       </file>
-      <file leaf-file-name=".gitignore" pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/.gitignore">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="150">
-              <caret line="10" selection-start-line="10" selection-end-line="10" />
-            </state>
-          </provider>
-        </entry>
-      </file>
     </leaf>
   </component>
   <component name="FileTemplateManagerImpl">
@@ -2514,7 +2503,6 @@
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/TextSizeControl.java" />
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/UserDictionary.java" />
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/CodeConverterDetailsActivity.java" />
-        <option value="$PROJECT_DIR$/app/src/main/res/values/strings.xml" />
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/ChimeeInputMethodService.java" />
         <option value="$PROJECT_DIR$/app/src/main/res/values/color.xml" />
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/MainActivity.java" />
@@ -2529,6 +2517,7 @@
         <option value="$PROJECT_DIR$/privacy-policy.md" />
         <option value="$PROJECT_DIR$/.gitignore" />
         <option value="$PROJECT_DIR$/app/src/main/java/net/studymongolian/chimee/OverlayTextView.java" />
+        <option value="$PROJECT_DIR$/app/src/main/res/values/strings.xml" />
         <option value="$PROJECT_DIR$/app/build.gradle" />
       </list>
     </option>
@@ -2572,27 +2561,6 @@
     </navigator>
     <panes>
       <pane id="PackagesPane" />
-      <pane id="AndroidView">
-        <subPane>
-          <expand>
-            <path>
-              <item name="Chimee" type="1abcf292:AndroidViewProjectNode" />
-              <item name="app" type="feadf853:AndroidModuleNode" />
-            </path>
-            <path>
-              <item name="Chimee" type="1abcf292:AndroidViewProjectNode" />
-              <item name="app" type="feadf853:AndroidModuleNode" />
-              <item name="res" type="d4f16f75:AndroidResFolderNode" />
-            </path>
-            <path>
-              <item name="Chimee" type="1abcf292:AndroidViewProjectNode" />
-              <item name="Gradle Scripts" type="ae0cef3a:AndroidBuildScriptsGroupNode" />
-            </path>
-          </expand>
-          <select />
-        </subPane>
-      </pane>
-      <pane id="Scope" />
       <pane id="ProjectPane">
         <subPane>
           <expand>
@@ -2622,6 +2590,22 @@
           <select />
         </subPane>
       </pane>
+      <pane id="Scope" />
+      <pane id="AndroidView">
+        <subPane>
+          <expand>
+            <path>
+              <item name="Chimee" type="1abcf292:AndroidViewProjectNode" />
+              <item name="app" type="feadf853:AndroidModuleNode" />
+            </path>
+            <path>
+              <item name="Chimee" type="1abcf292:AndroidViewProjectNode" />
+              <item name="Gradle Scripts" type="ae0cef3a:AndroidBuildScriptsGroupNode" />
+            </path>
+          </expand>
+          <select />
+        </subPane>
+      </pane>
     </panes>
   </component>
   <component name="PropertiesComponent">
@@ -2803,20 +2787,6 @@
       <option name="presentableId" value="Default" />
       <updated>1525155675484</updated>
     </task>
-    <task id="LOCAL-00039" summary="import and bug fixes">
-      <created>1536739032475</created>
-      <option name="number" value="00039" />
-      <option name="presentableId" value="LOCAL-00039" />
-      <option name="project" value="LOCAL" />
-      <updated>1536739032475</updated>
-    </task>
-    <task id="LOCAL-00040" summary="database upgrade">
-      <created>1536746729152</created>
-      <option name="number" value="00040" />
-      <option name="presentableId" value="LOCAL-00040" />
-      <option name="project" value="LOCAL" />
-      <updated>1536746729152</updated>
-    </task>
     <task id="LOCAL-00041" summary="unicode converter">
       <created>1536841097696</created>
       <option name="number" value="00041" />
@@ -3146,7 +3116,21 @@
       <option name="project" value="LOCAL" />
       <updated>1543002971449</updated>
     </task>
-    <option name="localTasksCounter" value="88" />
+    <task id="LOCAL-00088" summary="Version 3.1.0 release">
+      <created>1543279406910</created>
+      <option name="number" value="00088" />
+      <option name="presentableId" value="LOCAL-00088" />
+      <option name="project" value="LOCAL" />
+      <updated>1543279406911</updated>
+    </task>
+    <task id="LOCAL-00089" summary="corrected spelling error">
+      <created>1543280797038</created>
+      <option name="number" value="00089" />
+      <option name="presentableId" value="LOCAL-00089" />
+      <option name="project" value="LOCAL" />
+      <updated>1543280797040</updated>
+    </task>
+    <option name="localTasksCounter" value="90" />
     <servers />
   </component>
   <component name="ToolWindowManager">
@@ -3171,9 +3155,9 @@
       <window_info anchor="bottom" id="Build" order="11" visible="true" weight="0.33846155" />
       <window_info anchor="right" id="Gradle" order="5" />
       <window_info id="Structure" order="1" side_tool="true" weight="0.2497332" />
-      <window_info anchor="bottom" id="Debug" order="3" weight="0.39871794" />
       <window_info anchor="right" id="Device File Explorer" order="3" side_tool="true" weight="0.32977587" />
       <window_info anchor="right" id="Theme Preview" order="6" />
+      <window_info anchor="bottom" id="Debug" order="3" weight="0.39871794" />
       <window_info id="Favorites" order="6" side_tool="true" />
       <window_info anchor="right" id="Assistant" order="8" weight="0.32977587" />
       <window_info anchor="bottom" id="Messages" order="13" visible="true" weight="0.32984293" />
@@ -3195,8 +3179,6 @@
     <option name="myLimit" value="2678400000" />
   </component>
   <component name="VcsManagerConfiguration">
-    <MESSAGE value="Photo overlay: set typeface" />
-    <MESSAGE value="Photo overlay: set border" />
     <MESSAGE value="Photo overlay: shadow layer work" />
     <MESSAGE value="Photo overlay: bottom toolbar 4 buttons done" />
     <MESSAGE value="Photo overlay: background work" />
@@ -3220,7 +3202,9 @@
     <MESSAGE value="Chimee 3.0.0 release" />
     <MESSAGE value="bug fix for system keyboard horizontal keyboard layout" />
     <MESSAGE value="Version 3.0.1 release" />
-    <option name="LAST_COMMIT_MESSAGE" value="Version 3.0.1 release" />
+    <MESSAGE value="Version 3.1.0 release" />
+    <MESSAGE value="corrected spelling error" />
+    <option name="LAST_COMMIT_MESSAGE" value="corrected spelling error" />
   </component>
   <component name="XDebuggerManager">
     <breakpoint-manager>
@@ -3389,13 +3373,6 @@
         <state />
       </provider>
     </entry>
-    <entry file="file://$PROJECT_DIR$/app/src/main/res/values/strings.xml">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="1725">
-          <caret line="115" column="90" selection-start-line="115" selection-start-column="90" selection-end-line="115" selection-end-column="90" />
-        </state>
-      </provider>
-    </entry>
     <entry file="file://$PROJECT_DIR$/app/src/main/res/mipmap-hdpi/ic_launcher_round.png">
       <provider selected="true" editor-type-id="images">
         <state />
@@ -3598,7 +3575,7 @@
     </entry>
     <entry file="file://$USER_HOME$/Library/Android/sdk/sources/android-28/android/text/Layout.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="3960">
+        <state relative-caret-position="3435">
           <caret line="264" column="20" selection-start-line="264" selection-start-column="8" selection-end-line="264" selection-end-column="20" />
         </state>
       </provider>
@@ -3616,14 +3593,8 @@
     </entry>
     <entry file="file://$USER_HOME$/Library/Android/sdk/sources/android-28/android/widget/TextView.java">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="115725">
+        <state relative-caret-position="121050">
           <caret line="8070" column="16" selection-start-line="8070" selection-start-column="16" selection-end-line="8070" selection-end-column="16" />
-          <folding>
-            <element signature="e#202490#202491#0" expanded="true" />
-            <element signature="e#202525#202526#0" expanded="true" />
-            <element signature="e#202881#202882#0" expanded="true" />
-            <element signature="e#202915#202916#0" expanded="true" />
-          </folding>
         </state>
       </provider>
     </entry>
@@ -3644,10 +3615,17 @@
         </state>
       </provider>
     </entry>
+    <entry file="file://$PROJECT_DIR$/app/src/main/res/values/strings.xml">
+      <provider selected="true" editor-type-id="text-editor">
+        <state relative-caret-position="275">
+          <caret line="62" column="22" selection-start-line="62" selection-start-column="22" selection-end-line="62" selection-end-column="22" />
+        </state>
+      </provider>
+    </entry>
     <entry file="file://$PROJECT_DIR$/app/build.gradle">
       <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="285">
-          <caret line="19" column="1" selection-start-line="19" selection-start-column="1" selection-end-line="19" selection-end-column="1" />
+        <state relative-caret-position="435">
+          <caret line="29" selection-start-line="29" selection-end-line="29" />
         </state>
       </provider>
     </entry>
diff --git a/app/build.gradle b/app/build.gradle
index d2f7b8d..328d1d6 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -7,8 +7,8 @@ android {
         applicationId "net.studymongolian.chimee"
         minSdkVersion 14
         targetSdkVersion 28
-        versionCode 28
-        versionName "3.1.0"
+        versionCode 29
+        versionName "3.1.1"
     }
 
     buildTypes {
diff --git a/app/release/app-release.apk b/app/release/app-release.apk
index ae4ad07..0eaf7ee 100644
Binary files a/app/release/app-release.apk and b/app/release/app-release.apk differ