Context menu improvements

[henrikkauppi]

• Added a delete option to the marker list context menu
• Added context menu to the mask list in the Data panel with options to change color, duplicate, and delete the selected mask
• Added context menu to the surface list in the Data panel with options to duplicate, delete, and change the color and transparency of the selected surface

[rmatsuda]

Many thanks for this very useful PR @henrikkauppi! I found a small bug: if a mask is hidden and you press to change the color, the visibility is set to "show". However, if you press cancel in the color dialog, it still keeps the visibility set to "show", but the mask is not shown in the slices.

[henrikkauppi]

Many thanks for this very useful PR @henrikkauppi! I found a small bug: if a mask is hidden and you press to change the color, the visibility is set to "show". However, if you press cancel in the color dialog, it still keeps the visibility set to "show", but the mask is not shown in the slices.

Thank you for noticing the bug, it should fixed in 600cc97

[rmatsuda]

Thanks!