Basically when you open Gimp you have 3 windows. Toolbox,Main image window, and Layers window.
What happens is that you click on the paintbrush and nothing happens, you have to click it again to select the paintbrush. Then you try to paint on the image in the main window, nothing happens!, you try again and this time it works.
This is down to two reasons ,
1. Focus follows behaviour in Gimp
2. Click through behaviour in the Mac OS Xwindows
I decided to dedicate some time to fixing this so that I could use the gimp without screaming at the macbook and tell everyone how to fix it.
1. Fix the Gimp setup.
From the main gimp window select EDIT | PREFERENCES
Navigate down to Window Management
Change the two hints to KEEP ABOVE
Tick ACTIVATE THE FOCUSED IMAGE
tick SAVE WINDOW POSITIONS ON EXIT
Save the preferences
2. Fix Xwindows
Then open a terminal window and paste this in
defaults write com.apple.x11 wm_ffm true
And this
defaults write org.x.X11 wm_click_through -bool true
You can shut down Gimp and Xwindows and reopen Gimp to enjoy some sensible single click behaviour
