b0810f788c
Caused by {rBbf8507414889}
Above comit set the wrong cursors (WM_CURSOR_DEFAULT).
When releasing MMB, we need to return to WM_CURSOR_PAINT_BRUSH.
When exiting, we need to return to WM_CURSOR_DOT (since this is the
default cursor for the tool, see `_defs_gpencil_paint` >
`generate_from_brushes`)
Maniphest Tasks: T102650
Differential Revision: https://developer.blender.org/D16591