[mythtv] [PATCH] Fix PVR350 closing EPG goes to black screen

[jgmtfia Mr]

> The attached patch fixes the long standing problem of the screen going black
> when using a PVR350 after closing the EPG during livetv. 
> 
> It avoids the problem by turning off the OSD when the screen should be clear
> using the global Alpha and only enabling when there should be something
> displayed. 

Works great when exiting EPG.  

This problem also existed when entering the guide from live tv.  If
you move around enough in the guide, it eventually stays visible. 
This problem is still present.

Thank you for fixing the guide exit!