gtk_widget_queue_draw_area() vs gdk_window_invalidate_rect()

[Stefan Salewski <mail ssalewski de>]

I am a bit confused...

In the past I have used gtk_widget_queue_draw_area () when parts of my
drawing area has changed. (http://ssalewski.de/PetEd.html.)

In the gtk3-demo I just saw that gdk_window_invalidate_rect () is used.

Both seems to work fine, but I have no good idea about the differences
currently. Currently I was working on a toy chess program in Nim with
Unicode chess board pieces...