This is boolean drawing. This is something that I have discovered is unique to Macromedia Flash (currently Adobe Animate). It’s, in my opinion, the best and most natural way to do vector drawing especially when it involves animating. Here’s a little screen cap I made demonstrating boolean drawing.
Note that brushes of the same color “merge.” Also note that the eraser “subtracts.” Note the way fill works. If Wick Editor added this feature it would be genuinely a good alternative to Adobe Animate for people that just want to do basic animations.
Also, the “box selection” tool acts as a rectangle object that is “subtracted” from everything selected. I HIGHLY recommended all of these tools be implemented as it would make Wick a genuine and serious competitor and alternative to Adobe Animate (at least for people that just need basic drawing and animation tools).
No other program but Flash I have discovered uses this sort of boolean vector drawing and it’s the best way to do it. An old free program called “Vectorian Giatto” or something like that also did it but it’s no longer under development and it’s quite buggy and unusable anyway.
Not even Blender Grease Pencil has this much needed drawing feature.