I need to run a omxplayer into a kivy application. The problem is that when I start the omxplayer its appearance behind the kivy app, so it is not visible.
I tried using: Window.clearcolor = (0,0,0,0) but it doesn't work. I think that is because I'm running the app in a linux terminal.
How can I show the player in front of all applications?
I finally did it. Here the explanation.
Raspberry video core put the different application's screens  in differents layers. The terminal is in layer -127 and, according to kivy docs, kivy run in layer 0 by default. In my python code I run omxplayer with the next line of code:
Popen(['omxplayer', '--layer', '100000', '--live', '--refresh', '--video_queue', '4', '--fps', '30', '--win', '"0 0 800 480"', 'rtsp://192.168.0.88'])
The importart thing is --layer 100000, that is an option that allows us to choose the layer of omxplayer.
In my case, ran it in layers like 128 but it didn't work, so I suspect that kivy is not in layer zero. I ended putting 100000 and it works.
Its good to say that the kivy app keeps running in a lower layer, so every input signal (keyboard, buttons, etc.) is still working.
How to put omxPlayer on top of Kivy application in raspbian lite?