To reproduce:
- load two images
- create a segmentation for each one
- Select in the combo boxes image one and the segmentation for image two
-> The warning label tells you they do not fit, and buttons are disabled
- make the segmentation invisible
-> The warning label tells it is invisible, and buttons are disabled
- make the segmentation visible again
-> The warning label is gone, and buttons are disabled
Ideally the warning label should either display all current problems or the most pressing one. But they should not overwrite each other so that if the last one is solved previous ones are gone.