make ctrl+lmb and mmb work in a same way everywhere (like in browsers)

src/plugins/help/searchwidget.h

@@ -69,6 +69,7 @@ private slots:
     void searchingFinished(int hits);
 
 private:
+    bool eventFilter(QObject* o, QEvent *e);
     void keyPressEvent(QKeyEvent *keyEvent);
     void contextMenuEvent(QContextMenuEvent *contextMenuEvent);