mpv and xdg-screensaver3.5.1-1

[Barrowman]

running Mint 18.1 kernel 4.8.0-42-generic  Python 3.5.2 tkinter 3.5.1-1
I have written a python tkinter gui which works fine as long as I don't try to add

root.overrideredirect(1)

The video plays but with it in what seems to me a strange thing happens.
If I click on one of the buttons to display a video the screen flashes but I do not see the video.
However If I launch it from a terminal I can exit the program by pressing control-C twice and I can see this

Title:What a laugh (BSL)
VO: [opengl] 640x480 yuv420p
V: 00:00:13 / 00:01:03 (20%)


Exiting... (Quit)

If I leave it for a while before closing the program I get this

Title: What a laugh (BSL)
VO: [opengl] 640x480 yuv420p
V: 00:01:02 / 00:01:03 (99%)


Exiting... (Quit)

So it is playing but nothing appears on the screen.
Can anyone help please?

It seems that xdg-screensaver returns 4  
Does anyone know how this can be resolved please

[Barrowman]

I didn't mention that normally I run cinnamon but I have tried it on Mate and get the same [email protected]