Flickering when opened in a dialog

[SonReimer]

Now sometimes on opening and mostly on closing the dialog it shows a content only presentation for a short time (flickering)
Version 4.1.3/24.3.2

Testcase is the same as for #27

[mstahv]

I'd claim this to be greatness of Dialog + TinyMCE together. I don't have good ideas how to fix this without making a new Dialog implementation 🤷‍♂️ All good ideas accepted.