Texture unit mismatch between QOpenGLPaintEngine::drawTextureRect and QGLContextPrivate::bindTextureFromNativePixmap

I've been testing with the DUI "helloworld" example (libdui/examples/helloworld).

With the default graphics driver and DUI settings, the application will come up with just a background and white buttons or just all white. After some debugging, I found that Qt doesn't seem to match texture from pixmap binding with the texture unit it uses in QOpenGLPaintEngine::drawTextureRect. That is, in QGLContextPrivate::bindTextureFromNativePixmap textures are bound to GL_TEXTURE_2D, but subsequent copies come from GL_TEXTURE_RECTANGLE_NV, causing them to be empty.

So either bindTextureFromNativePixmap should be disabled in configurations requiring GL_TEXTURE_RECTANGLE_NV or the texture unit should be tracked for each texture so that drawTextureRect can do the right thing, or Qt should just move unconditionally to GL_TEXTURE_2D; I think it's supported everwhere TFP is.