showing the Shutdown dialog with applescript

I use this Applescript to quit all open applications and want to add the option to it to show the shutdown dialog at the end of the script. I found this shortcut (tap the on/off key, while holding the Ctrl key), which will be showing the dialog, but I don't know how to add it to the script.
Have anyone any idea?

tell application "System Events"

set allProc to displayed name of ( every process whose background only is false ) as list

end tell

-- quit each app

repeat with eachProc in allProc

set eachProc to eachProc as text

if eachProc ≠ "Finder" then

tell application eachProc to quit

end if

end repeat

tell application "Finder"

if visible is true then set collapsed of every window to true

end tell