TextEditor: improve line column button tooltip

Automatically hide the tooltip of the line column button in the editor
toolbar when the cursor leaves the widget.

Change-Id: Ia17f40029d0821584c8a804b44431a5d7e639066
Reviewed-by: hjk <hjk@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -207,6 +207,9 @@ void LineColumnButton::update()
 
 bool LineColumnButton::event(QEvent *event)
 {
+    if (event->type() == QEvent::Leave)
+        ToolTip::hideImmediately();
+
     if (event->type() != QEvent::ToolTip)
         return QToolButton::event(event);