No, DRI2 solves this problem which is not the same as the 2.5 branch. You need Mesa 7.2, Xorg 1.6.99.x and a suitable DRI2-capable video driver. Incidentally, it also fixes video and OpenGL app. rendering on Metacity Xrender and Mutter and KWin4.
With DRI2, rendering contexts just work the way you'd expect.