client: GL backend: disable ARB_FRAGMENT_PROGRAM by default

Fixes rendering when switching from YUV to RGB-based encodings (the fragprog would stay active and would therefore attempt to carry out colorspace conversion on RGB).

git-svn-id: https://xpra.org/svn/Xpra/trunk@923 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client.py

@@ -503,6 +503,7 @@ def do_configure_event(self, event):
         glMatrixMode(GL_MODELVIEW)
         glEnableClientState(GL_VERTEX_ARRAY);
         glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+        glDisable(GL_FRAGMENT_PROGRAM_ARB)
 
         if self.textures[0] == 0:
             self.textures = glGenTextures(3)