Bug#701903: Same problem...

GIMP 2.8.6, single window mode greys out "Maximize" option on right click of window bar, double clicking on title bar does nothing. Gnome 3 shortcut to maximize does nothing... so on and so forth. I haven't touched sessionrc (ever, didn't know it existed until I read this bug report). Going to W

Bug#701903: Another observation

Clicking Windows->Hide docks makes the maximize come back...