The paint tool can be used on a label set image with multiple labels. Using the paint tool on label A while drawing on label B, the tool contour is not shown and the locked label B is not masked.
However, unlocking label B allows to "paint over" the mask of label B. While doing this with the Paint tool, the contour of the paint tool while drawing is only shown while moving the mouse outside of the label B but not if the mouse is moved inside the label B (which will be painted over, nevertheless).
To reproduce:
- load a 3D image, open the multilabel segmentation plugin view, create a new label set image
- create and draw a new label on the first layer
- create and draw another label on the first layer (distinct color)
- unlock the first label
- use the paint tool while activating the second label
- see how the paint tool is drawn with a red contour while painting
- see how the red contour is not being drawn while moving the mouse inside of the first, unlocked label