, 0)
    for big-endian ARGB32 (i.e. ARGB8888) data.

    If *bbox* is passed, it defines the region that gets blitted. That region
    will be composed with the previous data according to the alpha channel.
    Blitting will be clipped to pixels inside the canvas, including silently
    doing nothing if the *bbox* region is entirely outside the canvas.

    Tcl events must be dispatched to trigger a blit from a non-Tcl thread.
    N