IrfanView 4.23 adds a feature I had not noticed until today by happenstance. Possibly only a hotkey as opposed to a feature.
Two fold use of Shift+V in IrfanView MUCH more convenient and MUCH faster than firing up photoshop to similarly expand canvas.
convert default to layer, expand canvas, stroke border of layer [or layer fx], save an PNG24 with transparency
Too bad IrfanView cannot add transparent canvas AFAIK.