Num Lock and Caps Lock always need to be explicitly handled by the modifier handler function, or they won't be correctly set if active at application startup, or if the lock state is changed while the application lacks focus since a key press for these keys will never be received. In these cases, the internal SDL modifier state can end up the inverse of the actual modifier state.
Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.
More extensive documentation is available in the docs directory, starting
with README.md
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