SVG rendering options (as described in the ICONS AND IMAGES section of the main fvwm documentation) can be utilized.
Note, a well behaved program, like fvwm, should listen to both _XSETROOT_ID and _XROOTPMAP_ID property changes and update itself correspondingly. However some programs listen only to one of them, so you should either use this option or not depending on what part is implemented by these programs. You should also use this option to get fast root-transparent menus in fvwm.
Rewritten and enhanced by fvwm-workers.