added icon in system tray

mainwindow.ui

@@ -20,6 +20,9 @@
   <property name="windowTitle">
    <string>MainWindow</string>
   </property>
+  <property name="windowIcon">
+   <iconset theme="/usr/share/icons/RsyncUI.png"/>
+  </property>
   <property name="toolButtonStyle">
    <enum>Qt::ToolButtonTextUnderIcon</enum>
   </property>
@@ -395,6 +398,7 @@
    <addaction name="action_Settings"/>
    <addaction name="actionAbout"/>
    <addaction name="actionAbout_Qt"/>
+   <addaction name="actionExit"/>
   </widget>
   <action name="DefaultSaveFolder">
    <property name="icon">
@@ -443,6 +447,20 @@
     <string>Click on menu button to download the entire folder</string>
    </property>
   </action>
+  <action name="actionExit">
+   <property name="icon">
+    <iconset theme="application-exit"/>
+   </property>
+   <property name="text">
+    <string>Exit</string>
+   </property>
+   <property name="toolTip">
+    <string>Terminate the program</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+Q</string>
+   </property>
+  </action>
  </widget>
  <customwidgets>
   <customwidget>