The erase draw with immediately previous drew image as pattern.(i.e. apply undo to a part of image.)

When using table as pointing device, if assign eraser function to that device, and then allow to use the Eraser function.

Note that depend upon OS api whether be able to eraser or not

In the free line or the free line with the pen pressure, drawing is equivalent to the eraser when the ⇧(shift) key and the ⌃(control) key are pressed.