Implemented "Always on Top" functionality.

This feature has been frequently requested by various users.

config.cc

@@ -94,6 +94,7 @@ Preferences::Preferences():
   doubleClickTranslates( true ),
   selectWordBySingleClick( false ),
   escKeyHidesMainWindow( false ),
+  alwaysOnTop ( false ),
 
   enableMainWindowHotkey( true ),
   mainWindowHotkey( QKeySequence( "Ctrl+F11,F11" ) ),
@@ -613,6 +614,7 @@ Class load() throw( exError )
     c.preferences.startToTray = ( preferences.namedItem( "startToTray" ).toElement().text() == "1" );
     c.preferences.closeToTray = ( preferences.namedItem( "closeToTray" ).toElement().text() == "1" );
     c.preferences.autoStart = ( preferences.namedItem( "autoStart" ).toElement().text() == "1" );
+    c.preferences.alwaysOnTop = ( preferences.namedItem( "alwaysOnTop" ).toElement().text() == "1" );
 
     if ( !preferences.namedItem( "doubleClickTranslates" ).isNull() )
       c.preferences.doubleClickTranslates = ( preferences.namedItem( "doubleClickTranslates" ).toElement().text() == "1" );
@@ -1268,6 +1270,10 @@ void save( Class const & c ) throw( exError )
     opt.appendChild( dd.createTextNode( c.preferences.audioPlaybackProgram ) );
     preferences.appendChild( opt );
 
+    opt = dd.createElement( "alwaysOnTop" );
+    opt.appendChild( dd.createTextNode( c.preferences.alwaysOnTop ? "1" : "0" ) );
+    preferences.appendChild( opt );
+
     {
       QDomElement proxy = dd.createElement( "proxyserver" );
       preferences.appendChild( proxy );

config.hh

@@ -158,6 +158,7 @@ struct Preferences
   bool doubleClickTranslates;
   bool selectWordBySingleClick;
   bool escKeyHidesMainWindow;
+  bool alwaysOnTop;
 
   bool enableMainWindowHotkey;
   HotKey mainWindowHotkey;

mainwindow.cc

@@ -386,6 +386,9 @@ MainWindow::MainWindow( Config::Class & cfg_ ):
   ui.menuView->addSeparator();
   ui.menuView->addAction( &showDictBarNamesAction );
   ui.menuView->addAction( &useSmallIconsInToolbarsAction );
+  ui.menuView->addSeparator();
+  ui.alwaysOnTop->setChecked( cfg.preferences.alwaysOnTop );
+  ui.menuView->addAction( ui.alwaysOnTop );
 
   // Dictionary bar
 
@@ -609,6 +612,11 @@ MainWindow::MainWindow( Config::Class & cfg_ ):
   // Initialize global hotkeys
   installHotKeys();
 
+  if ( cfg.preferences.alwaysOnTop )
+  {
+    on_alwaysOnTop_triggered( true );
+  }
+
   // Only show window initially if it wasn't configured differently
   if ( !cfg.preferences.enableTrayIcon || !cfg.preferences.startToTray )
   {
@@ -2772,6 +2780,35 @@ void MainWindow::on_rescanFiles_triggered()
   installHotKeys();
 }
 
+void MainWindow::on_alwaysOnTop_triggered( bool checked )
+{
+    cfg.preferences.alwaysOnTop = checked;
+
+    bool wasVisible = isVisible();
+
+    Qt::WindowFlags flags = this->windowFlags();
+    if (checked)
+    {
+        setWindowFlags(flags | Qt::CustomizeWindowHint | Qt::WindowStaysOnTopHint);
+        mainStatusBar->showMessage(
+              tr( "The main window is set to be always on top." ),
+              10000,
+              QPixmap( ":/icons/warning.png" ) );
+    }
+    else
+    {
+        setWindowFlags(flags ^ (Qt::CustomizeWindowHint | Qt::WindowStaysOnTopHint));
+        mainStatusBar->clearMessage();
+    }
+
+    if ( wasVisible )
+    {
+      show();
+    }
+
+    installHotKeys();
+}
+
 void MainWindow::zoomin()
 {
   cfg.preferences.zoomFactor += 0.1;

mainwindow.hh

@@ -376,6 +376,7 @@ private slots:
   void on_showHideHistory_triggered();
   void on_exportHistory_triggered();
   void on_importHistory_triggered();
+  void on_alwaysOnTop_triggered( bool checked );
   void focusWordList();
 
   void updateSearchPaneAndBar();

mainwindow.ui

@@ -61,7 +61,7 @@
      <x>0</x>
      <y>0</y>
      <width>653</width>
-     <height>18</height>
+     <height>21</height>
     </rect>
    </property>
    <widget class="QMenu" name="menuFile">
@@ -432,6 +432,20 @@
     <string>&amp;Import</string>
    </property>
   </action>
+  <action name="alwaysOnTop">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Always on Top</string>
+   </property>
+   <property name="toolTip">
+    <string>Always on Top</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+O</string>
+   </property>
+  </action>
  </widget>
  <customwidgets>
   <customwidget>