I know that this has come up with other users in other threads. I am starting a new thread because: The cause of my problem is different and
the ongoing problem has not been fixed and
the other threads are so long my post would not be seen.

I have Gimp 2.6 on my system (i7, Win 7 + all updates, 8gb RAM, and so on) and have been running it successfully for a couple years now. I just downloaded Gimp 2.8 and assumed it would overwrite 2.6 but it did not, which is fine by me.

The problem: In multi-window mode I click on a tool icon and it works fine. I click on another icon and no response. I have to click on the display window border, then the tool I want and it selects it. But the next tool selection fails until I click on the display window again. In single window mode, I have the same problem but now must clock somewhere outside of Gimp 2.8 before I can select a new tool.

Gimp 2.6 is still on my system and still works as it always has. Considering that right now Gimp 2.6 works and Gimp 2.8 does not suggests that the problem is something on the dev end and not with other software or the operating system. I do not have Kasperty or the other programs others have tried to link this issue to.

Anyway, I've enjoyed using Gimp 2.6 and will continue until some future update corrects this problem. I did not notice if I could download Gimp 2.6 still from the dev site, but if not I cannot continue to recommend this program...