As update to https://feedback.objo.dev/bug/1295, unfortunately this still isn't working correctly.
I have a Container Control as a statusbar with 2 Labels and 1 Canvas controls in it.
This subclassed Container Control has a width of 360 px and a height of 32 px.
The Canvas control is at the right and has a lock at the right and at the bottom and shows a red bullet.

When I add this statusbar in the window the width is changed to 600 px and the statusbar is locked at left, right and bottom.
When I run the program I expect the canvas still to be at the right side of the statusbar but it's not.
