video bleeds through somewhat between sessions

[Mikus Grinbergs]

>> When I am looking at the (full-screen) video output, if what I see
>> involves a 'video overlay' -- that's fine with me.  But when I
>> "switch away" from the 'session' displaying the video output, I
>> don't want "interference" to what I'm currently looking at (whether
>> that interference comes from a 'video overlay', or from whatever).
> 
> Then the video application needs to stop the video or change the
> demensions of the overlay window.  The hardware is only doing what
> it is told to do.

I think you and I are agreed on the undesirability of having the 
video affect what is currently shown on the XO screen, when the user 
has caused what is now being shown on that screen to be taken from a 
'session' other than the 'session' containing the video application.


But the video *application* typically does not know if the user is 
looking at its "output screen", or not.  At best, the operating 
system which lets the user __switch__ to a different 'session', 
could send a "signal" to the transferred_away_from session -- but 
even if told, does the video *application* support changing its 
video output ?

I'm thinking of the example provided by the X-window system -- when 
one (non-transparent) window has the focus, it somehow PREVENTS 
having users see the content of whatever is "behind".  Maybe the 
facility used to draw XO screens can similarly PREVENT having users 
see any content of whatever 'sessions' are NOT being shown.

mikus