get-handle in window<%>
Returns an exact integer representing a handle to the window in the current platform's GUI toolbox. Cast this number from a C long to a platform-specific C type:
Windows: HWND
Mac OS X: WindowRef for a
top-level-window<%>object, ControlRef for other windowsX: Widget*
Some windows may not have a representation in the platform's GUI level,
in which case the result of this method is 0.