Brush keybind black border

[joshua-dean]

very cool. one weird thing i noticed is that if you click the brush buttons and/or annotation size buttons and then use a keybind for the same to toggle, then your previously clicked option stays with a black border. not a huge deal, just unexpected and maybe slightly confusing. clearly not introduced in this pr so dont have to fix it now

steps to reproduce:

1. click on the brush/erase button in the toolbox
2. use a keybind (g or e) to toggle or switch brush mode
3. the active class disappears, but a black border remains

Originally posted by @TrevorBurgoyne in #188 (review)

[joshua-dean]

As mentioned here, I can reproduce this in Chrome but not in Firefox.