Apple script to set all background on all displays and all spaces

background.scpt

set displaylist to {}

tell application "System Events"
	set theDesktops to a reference to every desktop
	repeat with n from 1 to count of theDesktops
		tell item n of theDesktops
			set dn to display name
			set p1 to picture
		end tell
		set k to {dn:p1}
		set end of displaylist to {d:dn, p:p1}
	end repeat
end tell

set numSpaces to 16

tell application "System Events" to key code 122 using {command down, control down, option down, shift down}

repeat (numSpaces + 1) times
	
	tell application "System Events"
		set theDesktops to a reference to every desktop
		repeat with n from 1 to count of theDesktops
			tell item n of theDesktops
				set dn to display name
				repeat with k from 1 to count of displaylist
					set pp to item k of displaylist
					set ddn to d of pp
					set ppn to p of pp
					if ddn = dn then
						set picture to ppn
					end if
				end repeat
			end tell
		end repeat
	end tell
	
	
	delay 1
	
	tell application "System Events" to key code 124 using {command down, control down, option down, shift down}
	
end repeat

tell application "System Events" to key code 122 using {command down, control down, option down, shift down}