Convenience function that calls queue_draw_region on the region created from the given coordinates.
The region here is specified in widget coordinates. Widget coordinates are a bit odd; for historical reasons, they are defined as this->window coordinates for widgets that return true for get_has_window, and are relative to this- >allocation.x, this->allocation.y otherwise.
width or height may be 0, in this case this function does nothing. Negative values for width and
height are not allowed.
| this |
a Widget |
| x |
x coordinate of upper-left corner of rectangle to redraw |
| y |
y coordinate of upper-left corner of rectangle to redraw |
| width |
width of region to draw |
| height |
height of region to draw |