The external opengl context must be specify when creating
our OpenGL context (glx) or just after (wgl).
When calling glXCreateContext or wglShareLists, the
external opengl context must not be current.
Then our gl context can be current in the gl thread while
the external gl context is current in an other thread.
See tests/examples/clutter/cluttershare.c
Partially revert previous commit. It's not an issue with glimagesink
Xoverlay interface. It's always the same intel bug with direct
rendering redirection (the one that affects each opengl application
with compositing managers). It works fine with DRI2 and UXA
acceleration. Still leaving effects disabled because I'm testing intel
hardware that doesn't support FBOs.
GLimagesink XOverlay interface doesn't seem to work with composite
redirection on intel (and I believe ati too). Windows aren't
redirected offscreen at all. This commit just shows that the example
correcty works with ximagesink. The most evident difference I see is
that glimagesink reparents the xoverlay window into its own while both
x and xvimagesink destroy their window and render directly to the
xoverlay one.
Revert the "move windows" thing from commit
175f7a707bc922f3facc63e7d9b6d01f9bb6b1b0
Windows are offscreen who cares about their position? If you see the
windows something is going wrong with composite redirection.
This reverts commit 96e4ab18c2cf9876f6c031b9aba6282d0bd45a93.
You should have asked first. And you would have been told "no",
because it causes people on development branches to do a huge
amount of extra work.
