Added basic window widget - can move and resize it.
Change example wrapper to accept any widget class as a parent.
Draw widgets relative to their ancestor window position (if they have a parent window).
Lock input to a window when it has focus.
Clear widget temp input state when the lockInputWindow changes.
Don't clear button pressed state when the mouse leaves the button.
Allow widgets to lock input to themselves (and their children). Used by buttons when pressed down and waiting for release.