The window manager expects to find two XPM files for each icon specified in the configuration files as ICON. They should be named like this:
_16x16.xpmA small 16x16 pixmap.
_32x32.xpmA normal 32x32 pixmap.
_48x48.xpmA large 48x48 pixmap.
Other pixmap sizes like 20x20, 24x24, 40x40, 48x48, 64x64 might be used in the future. Perhaps we need a file format that can contain more than one image (with different sizes and color depths) like Windows'95 and OS/2 .ICO files.
It would be nice to have a feature from OS/2 that varies the icon size with screen resolution (16x16 and 32x32 icons are quite small on 4000x4000 screens ;-)
When compiled with Imlib image library all of Imlib's image formats (bmp, jpeg, ppm, tiff, gif, png, ps, xpm on my machine) are supported. Use them by specifying the full filename or an absolute path:
A PPM icon in your IconPath.
An PNG image with absolute location.