Code review comment for lp:~kaihengfeng/unity/lp1292830

> > I'm, I see the approach here, but I'm not much a fan of some things...
> >
> > You told me that instead of recalling set-texture on any element, just
> > damaging its area isn't enough? What's the problem here?
>
> https://www.khronos.org/registry/OpenGL/extensions/NV/NV_robustness_video_memo
> ry_purge.txt
>
> Looks like the link in the commit log was mistakenly deleted when I did force
> push, here's the excerpt:
>
> The NVIDIA OpenGL driver architecture on Linux has a limitation:
> resources located in video memory are not persistent across certain
> events. VT switches, suspend/resume events, and mode switching
> events may erase the contents of video memory. Any resource that
> is located exclusively in video memory, such as framebuffer objects
> (FBOs), will be lost. As the OpenGL specification makes no mention
> of events where the video memory is allowed to be cleared, the
> driver attempts to hide this fact from the application, but cannot
> do it for all resources.
>
> > Is this due to the fact that since the texture is saved as xrandr format,
> then
> > the driver just deletes that on S3?
>
> This I can't answer, but I think the excerpt above should've explained it.
>
> > In any case I'd prefer that this thing would be done at DecorationsWidgets
> > level so that it can be esily applied to all elements, and not just per
> item.
> >
> > Let me know what's feasible, and I'll try to figure out the best approach,
> > avoiding to be too much specific.
>
> The link gives a super simple example:
>
> create_gl_context();
> create_resources();
> while (1) {
> update_world();
> if (GetGraphicsResetStatusARB() == PURGED_CONTEXT_RESET_NV) {
> delete_resources();
> create_resources();
> }
> render_frame();
> }
>
> I am not sure if it's feasible in current architecture though - maybe logind
> signal is the only way to go?

I would not rely on an extension that might not be available. Btw I guess Marco he's suggesting to apply the fix inside TexturedWindow, so removiong the logic from the *Manager class. You just need a way to get the "onResume" signal there.