Bug 395451

When I try to remove a brush preset from the tag "My Favorites" it stays in there. Even after a restart of the program its still in "My Favorites" and got it's tag back.
This only seems to affect the presets that are in "My Favorites" by default. I can remove bushes I've added manually just fine.

Steps to Reproduce.
Select "My Favorites" in the Brush Presets Docker.
Right-click on a preset e.g e)_Marker_Dry
Select "Remove from this Tag", from the context menu.

Expected behavior: The preset is removed and disappears from the docker.
Actual behavior: Nothing happens.

The same is true for other default tags although I don't see it as an issue there. But the "My favorites" tag should be treated different since it should be really  the artists favorites only, not its favorites + some presets someone thought could fit.