GUI/v22 some toolbar/mask actions broken

1D:

• no button to center image - done in !2604 (merged)
• "arrow" icon has no function - removed in !2605 (merged)
• "panel" icon initially off though panel is shown - fixed in !2605 (merged)

1/2D:

• crash upon "center" icon - done by 21jun24
• "zoom" icon (hand) on/off does not correspond to actual zoom or not-zoom behavior - in !2606 (merged) fixed for 2D; icon removed for 1D

2D:

• polygon mask cannot be created - a setVisible(true) in VertexOverlay::update_view would help; so the problem is with visibility - fixed in !2617 (merged)
• ellipse mask cannot be resized by dragging its corner - partly resolved in !2609 (merged), partly dependent on #908 (closed) - fixed in !2611 (merged)
• mask jumps when moved - fixed 26/27jun24
• sizehandle enum overly complicated - cleaned up in !2612 (merged)
• line masks and projections are mixed: they have the same icons and both shown in projection plot - done by 21jun24
• "lamp" button has no effect - fixed in !2625 (merged)
• overlay hierarchy, signalling, registering too complicated; also check serialization
• result of moving vertex is only shown with delay (e.g. when next action is selected)
• mouse icon should change in move-mask mode (it does so for lines) - fixed in !2630 (merged)
• mask and roi related GUI suite tests are currently disabled - fixed in !2628 (merged)
• in mask panel, we cannot select items - fixed in !2627 (merged)

See also

• #618 (closed) Mask & ROI related issues
• #910 (closed) missing button/menu/keybinding to remove mask - in !2626 (merged) provided delete button. Other handles are just nice to have, to be done post r22.
• #958 (closed) ROI broken
• #983 (closed) context menu
• #988 (closed) masks don't transform upon zoom or resize - fixed in !2631 (merged)