[kde] AboutTab::showEvent(): Pass the event to the base class.

TODO: Check other QWidget subclasses to see if this is needed there.

src/kde/config/AboutTab.cpp

@@ -634,6 +634,9 @@ void AboutTab::showEvent(QShowEvent *event)
 		d->checkedForUpdates = true;
 		d->checkForUpdates();
 	}
+
+	// Pass the event to the base class.
+	super::showEvent(event);
 }
 
 /** UpdateChecker slots **/