Mirroring a drawable buf in DLangUI?

[Dukc via Digitalmars-d-learn]

I am using the DrawRescaled method of DrawBuf[1] of DLangUI To 
draw a PNG image to a CanvasWidget[2] subclass. It has a minor 
issue of the box bounds showing in area that shoud be transparent 
but otherwise works well.

My question is, does anybody know a way to draw that image 
backwards without making another PNG file to do so? I tried to 
pass a dstrect with negative width but that results in nothing 
being drawn.

1: 
http://buggins.github.io/dlangui/ddox/dlangui/graphics/drawbuf/DrawBuf.html
2: 
http://buggins.github.io/dlangui/ddox/dlangui/widgets/controls/CanvasWidget.html