Gregory Maxwell wrote:
I don't know what software you're using, but
this is trivial in gimp.
Create/open your transparent png. Set your gimp background color to
the desired background color. Save the png, make sure that 'save
background color' is checked and ''save color values from transparent
pixels" is unchecked.
I tried fiddling with those checkboxes but that the currently selected
background color would have any effect didn't occur to me. Thanks