Modifier keys on Mac and ruby API confusion

[slbaumgartner]

@eneroth3

The API provides a constant VK_CONTROL but no VK_OPTION. The VK_ALT and VK_COMMAND constants however have the same value, suggesting Alt and Command are just different names for the same key.

On Mac, Option and Alt are equivalent. Some Mac keyboards label the key option, some label it alt, some label it both, and some use the symbol. Given this somewhat complicated mess, SketchUp chose to use only VK_ALT. Both control and command are separate keys, neither of them equivalent to option/alt.

The values of the key code constants are:

VK_ALT
524288
VK_CONTROL
262144
VK_COMMAND
1048576