wbar background not updated to new desktop wallpaper about wbar HOT 2 OPEN

Sorry, I missed the following:

What is the expected output? What do you see instead?

wbar should update the background when a property notification event is fired 
for _XROOTPMAP_ID or _XROOTMAP_ID (tint2 also uses that approach); patch is 
attached.

Same thing with a composite manager.  wbar does not refresh when background 
wallpaper change  (either by changing the wallpaper or swiching to another 
virtual desktop in xfce 4.12.  A square around the bar stay like the old 
background.  A right click in the area trigger the refresh.

BT