Just a quick vote & thought here; I voted to keep it orange, as orange is pretty close to red which usually means "Stop! You're about to do something drastic!" - like "stopping"/closing the program currently in use.
Whereas green typically means "Go!"
and (an even brighter shade of green) would be great for the maximize button (Fullscreen = maximum "Go!"), and finally either yellow or blue for the minimize button.
When I'm working on such windows min/max/close buttons, I like to make the primary color shades a little subdued, and incorporate a much brighter shade on hover to act as a visual indicator that the cursor has found its target, as well as which particular target via the bright "pop" of color.