Repro steps: build, install and run the attached test program TestViewport.apk Run on Sapphire with Froyo. The program clears the screen to blue, then draws a full screen white quad that is alligned to the screen. (Therefore the whole screen should appear to be white.) Note that screen is all white. Rotate screen 90 degrees. Expected: screen is still all white. Actual: screen is blue with offset white rectangle. This bug only happens on Sapphire, it works correctly on Passion. What happens: I think the bug is that the gl.glViewport() call in onSurfaceChanged() is being ignored by the OpenGL driver. NOTE: If a gl.glViewport call is added at the beginning of the onDrawFrame() call (which means it is called before every draw), the program runs correctly.