I want to make a GdkRectangle clickable so that I can select it and get a dot in every corner of the rectangle, implying that the user can move or resize the rectangle.
Is there an event that triggers when a GdkRectangle is clicked? What's the syntax of the accompanying g_signal_connect command?
GdkRectangle isn't meant to be used like that. It isn't a widget, but just a way to refer to a rectangular area of pixels. You should probably use something like GtkLayout but without knowing exactly what you're doing, I can't say for sure.