I was wondering if it is possible to overlay a keyboard layout for touch input over emulationstation screen and the installed / running emulators on GPIO trigger, e.g.: GPIO X triggered, keyboard layout appears (transparent?) and disappears after "soft" return key is pressed. I am able to read the touch coordinates and can generate key events (udev) but I am not able to show a general overlay on emulationstation (like soft keyboard layout).
I tried dispmanx demo hello_dispmanx with several layers and it worked for dosbox, but not for scummvm or snes for example and not on the emulationstation menus at all. What surprised me was the fact, that on a "normal" raspberry image (jessie lite) with an "apt-get install scummvm" the hello_dispmanx overlay example on scummvm worked
My question: Does anybody know if it is possible to dynamically (by activating a GPIO) "overlay" any graphics over Emulationstation or on any of the installed emulators and how?