Você tem alguma solução?
Eu encontrei o mesmo problema, então criei uma solução rápida de hackear com o AppleScript:
set spacenumber to 4 -- how many spaces do you have?
-- Try to get number of spaces from System preferences
tell application "System Preferences"
reveal anchor "shortcutsTab" of pane id "com.apple.preference.keyboard"
tell application "System Events" to tell window "Keyboard" of process "System Preferences"
set spacenumber to count (UI elements of rows of outline 1 of scroll area 2 of splitter group 1 of tab group 1 whose name begins with "Switch to Desktop")
end tell
quit
end tell
tell application "System Events"
set _desktops to every desktop
if (count of _desktops) > 1 then
-- if you have multiple displat (eg: external monitor) ask which
display dialog "Choose your screen." buttons (get display name of every desktop) default button 1
set _display to the button returned of the result
else
-- else set the one display as selected
set _display to display name of the first desktop
end if
set new_file to choose file with prompt "Choose an image."
repeat with i from 0 to (spacenumber - 1)
delay 1
tell (every desktop whose display name is _display) to set picture to new_file as alias
tell process "WindowServer" to key code {124} using control down -- Go to the next space
end repeat
end tell
É bom para mim agora.
Atualização: number of spaces
getter adicionado de: link