This looks like an issue with the gfxlib's window message handling.
The default keyboard shortcut to switch layouts is ALT+SHIFT (at least on my Windows XP VM), but FB skips ALT keydown/keyup events (instead of passing on to DefWindowProc()) to avoid opening the window menu. I wonder whether that's even needed.
Changing that doesn't seem to fix the problem of being unable to switch the layouts though, so apparently there's more to it.
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This looks like an issue with the gfxlib's window message handling.
The default keyboard shortcut to switch layouts is ALT+SHIFT (at least on my Windows XP VM), but FB skips ALT keydown/keyup events (instead of passing on to DefWindowProc()) to avoid opening the window menu. I wonder whether that's even needed.
Changing that doesn't seem to fix the problem of being unable to switch the layouts though, so apparently there's more to it.