Mask bugs in GUI

• add mask, press the "lamp" button to see pixelized masks --> crash. If masks are not freshly created or resized but just loaded as is, everything works.
• on resizing polygon or ellipse mask the view is not updated
• newly created or selected mask do not disappear on pressing "lamp" button. After unselecting data and selecting it back the "lamp" works properly again
• add any change/move to masks, deselect data and select again --> crash
• due to non-negative limits for mask coordinates masks are cut or squashed to zero size after creation

To be updated.