#77 gluBuild2DMipmaps +wx seg-faults on Linux

[Mike C. Fletcher]

The OpenGLContext/tests/nehe7.py test fails on Linux
with a segmentation fault during the
gluBuild2DMipmaps(GL_TEXTURE_2D, 3, ix, iy, GL_RGBA,
GL_UNSIGNED_BYTE, image) call.

[Mike C. Fletcher]

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Again, only fails under the wxPython context (not the glut
one). There appears to be something going on in the
initialisation of the wxPython context under GTK which
results in getting a very limited context created, or
possibly even a broken one. I can't see anything obviously
wrong with what's being done, but something is obviously
causing a problem.

[Mike C. Fletcher]

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Just making the summary line match the current understanding
of the bug.

[Mike C. Fletcher]

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Okay, this is now fixed, though the fixes are not the most
beautiful things in the world. Turns out that the wxPython
wxGLCanvas only creates the actual context during a "window
realization" callback. The fixes involved providing a new
customization point in the context base class, and a
specialization in the wxPython context. There is also a new
flag in the wxPython context which provides a last resort
attempt to initialize during the paint event. This appears
to work in most cases, though the meta-test is showing a few
rendering artifacts.