#303 Request re ttk::sizegrip

[Peter Caffin]

On many platforms (Mac and Windows at least), resizing from the window decoration corners simply drags around the frame to the size you want, then configures the window contents when a ButtonRelease-1 event is received.

ttk::sizegrip by contrast configures window contents throughout the resize drag. It would be excellent if we there were an option to choose which of these two behaviors we want the ttk::sizegrip to use.