Actually, you can use emulationstation for windows as a theme editor. I think that it would be very hard to adjust the objects dragging them with the mouse cursor and people will end up using text editor anyways.
I just discovered this, judging from the screenshots this is exactly what i've been looking for. retropie doesn't support php5 anymore.
I installed php7 + sql3 manually (edited the install script to not check for php5 dependencies) but it doesn't seem to work. no files are inside /www. anyone can help?