Key Location

I noticed that keyLocation is not part of AreaKeyEvent. It is basically the indicator of whether the user pressed the right shift key or left shift key. Alternatively, it indicates if the user pressed a num pad number of a standard number.

SWT supports it: https://help.eclipse.org/latest/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/swt/events/KeyEvent.html

Web Browser JS supports it too: https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/location

By the way, I needed the keyLocation to make a distinction between right and left shift (or control) keys while playing [Glimmer Tetris](https://github.com/AndyObtiva/glimmer-dsl-libui/blob/28396dedb0d3ec4213ac94d20f922c36f13c11a6/examples/tetris.rb). For now, I resorted to another solution (make shift turn right and control turn left).


Thanks for providing such a great GUI library.

Cheers.