Untill now the MenuBar was not visible untill you pressed the
alt-key, which made it visible. Sadly after that it was not
possible to hide it again. This patch fixes that.
I have no idea why, I think it might be some timing issues while
initializing the webengine, but when using runJavaScript() in
the WebEngineView without referencing it with the id of that
QML object it just throws the error that it doesn't know what
runJavaScript() is. When we use the ID then it just works
for some reason.
