Add Erase Fill Brush in Grease Pencil

Hello to all Blender developers, special thanks for creating Grease Pencil, the dream tool for 2d animators! I've been using Grease pencil for a few months now and I must say that version 2.92 is now a complete tool! However, I found limits in creating fills! So I thought I'd come up with a suggestion: "Erase Fill Brush". This way you can add or subtract fill quickly, a very useful function for creating shadows and highlights in cell shading and more! I am attaching the example image that explains this function in detail. IMPORTANT: You could also add a subtraction function to the draw mode, not necessarily create an erase brush!