DrawingAreaDrawFunc

typealias DrawingAreaDrawFunc = (drawingArea: DrawingArea, width: Int, height: Int) -> Unit

Whenever @drawing_area needs to redraw, this function will be called.

This function should exclusively redraw the contents of the drawing area and must not call any widget functions that cause changes.

param drawingArea the GtkDrawingArea to redraw
param width the actual width of the contents. This value will be at least as wide as GtkDrawingArea:width.
param height the actual height of the contents. This value will be at least as wide as GtkDrawingArea:height.