[Mesa-users] another serious issue with OpenGL on Linux

[Daniel Trstenjak]

Hi Gianluca,

> My application creates a QGLWidget with a default rendering context
> (so, double buffered).  It works fine, until I try to copy a part of
> the front buffer into the back buffer. From that point on, it starts
> flickering, as if it renders in the front buffer directly.

we had pretty much the same issue with Qt + Mesa on Linux.

Since Qt 5.7, the xcb plugin will switch from double buffer to single buffer
when trying to get a valid context before reducing the multisampling.

So you've to make sure to never request a context with a multisampling
that's not supported.

Greetings,
Daniel