While the sticker tool is really great it might be awesome to have texture paint so brushes and tools instead of using a solid color use an image instead.
I imagine you can have the option as a button somewhere in the color picker then it opens a browse for an image.
If this mode is activated aditional options appear on the top of the picker (which changes to a preview of the image) that allow you to scale/rotate the sample and create a seamless texture (by flipping horizontally and vertically the image).

Then your brushes will paint with that image colors (so we can create patterns rather easy)

Example, simple hatches: you have an image with hatches, you select that from the color picker and then chosing any tool it auto creates hatches.

That would be great