As far as I tested it works fine with no problem.
Keep up the good work.
Regarding implementing the same feature in the contiguous selection tool, I don’t think it’s necessary because personally, if the lineart is complex enough other tools become more useful(colorize mask, freehand selection, even just a brush to make the base clipping area, or the regular contiguous selection to select the outside region and invert it). But opinions on this may vary.