of*Window/ofEvents: pressedKeys accumulate in special cases

In some cases, when modifier keys are used, the pressedKeys set will accumulate keys.

This happens because "modifier-up" messages are not sent in the same way as normal and special keys.

To test, watch the size of the pressedKeys:

cout << pressedKeys.size() << " num pressed keys " << endl;

Press a modifier key and a normal key -- say ctrl-a. If the 'a' is lifted first, then the modified-a key int is removed from the pressedKeys set. If CTRL is released before the 'a', then the non-modified-a key-up int is sent, and it is not erased from the pressedKeys set. If this is repeated with different modifier+key downs / ups the accumulation occurs.

Ultimately, there needs to be better handling of modifier keys. Perhaps there is a way to use the modifier masks keep track of modifier keys with a call to glutGetModifiers() in the keyboard_cb and keyboard_up_cb static methods?

It looks like progress has been made toward this in ofConstants.h

#define OF_KEY_CTRL         0x0200
#define OF_KEY_ALT          0x0300
#define OF_KEY_SHIFT        0x0400

But it seems to have stopped there.

I'm happy to work on this -- any suggestions on a strategy? Perhaps this is already being addressed of 007?

Start by tracing pressedKeys handling through of*Window/ofEvents and the static keyboard_cb and keyboard_up_cb methods, then inspect the modifier constants in ofConstants.h. Reproduce the ctrl-a cases described, including releasing CTRL before A. Done means modifier and normal key-up events remove the correct entries without accumulation.