Tray: Show settings dialog on click if it's not active

Before, you often had to click twice to bring the window
to the front, because the first click would close it.

src/gui/owncloudgui.cpp

@@ -150,7 +150,7 @@ void ownCloudGui::slotOpenSettingsDialog()
 {
     // if account is set up, start the configuration wizard.
     if( !AccountManager::instance()->accounts().isEmpty() ) {
-        if (_settingsDialog.isNull() || !_settingsDialog->isVisible()) {
+        if (_settingsDialog.isNull() || QApplication::activeWindow() != _settingsDialog) {
             slotShowSettings();
         } else {
             _settingsDialog->close();