[Project_owners] how to merge PNGs for toolbar?

[Eric H. Jung]

Hi,

I'm following the directions here:
http://developer.mozilla.org/en/docs/Custom_Toolbar_Button#Required_tools
for making a toolbar icon for FF 1.5.

I created 4 separate PNGs (2 @ 24x24, 2 @ 16x16).

Can anyone recommend Windows-based software to assist in merging these
PNGs into a single PNG? I don't have Photoshop. Paint Shop Pro might
work but seems overkill.

Thanks,
Eric