I solved the problem, but i don’t know what really was the point.
I tried the following:
I started by putting a RWML Switch Styled stack in the TopBar Drop Zone.
The content oft he Switch Styled Stacks was:
„Sprache wählen: “
„Select your language: “.
Both flags are bigger, the width is set to “25”.
I had the described issue.
Next step was using the RWML Switch Image stack. I put the picture in there, the issue remained the same.
Next i took other (smaller) flag pictures in the Switch Image stack. No change.
Then i tried with different sizes in the custom sizing of the TopBar. And then for the very first time, the TopBar had the right size, remained in this size when scrolling and the flag was positioned in the TopBar itself. I just had to set the padding in the custom sizing to 0 (Zero). But the result looked awful, no option to use these settings.
All the time i was in contact with Robb from Joe Workman. Thanks a lot!
Then i got in contact with Tsooj Media, as Robb has realized, that Anugyan (who is using TopBar Extra Zone with RWML as well and it works) was using RWML 2.0 but me i had 1.1.2.
Joost from Tsooj was so kind to give me the opportunity to try the beta of RWML 2.0.
So i tried this one.
With the Switch Image Stack the issue remained the same.
But with the Switch Styled Stack i got it working!
As i am using smaller flags now, the input in the stack is:
No width declaration, size is original.
I have two drop zones in the TopBar, i have a RWML Content stack in every drop zone and the RWML Switch Styled Stack in every RWML Content stack.
Maybe it would have worked this way with RWML Switch Styled Stack 1.1.2 too and the point was, that i had the width declared when first using it.
But with the Switch Image Stack it does not work the same, even with RWML 2.0.
In the end, i got it working now and i am really happy about it!
Thanks to all involved.