property pfSkipHiddenFolders : false

on run
	tell application id "com.omnigroup.OmniFocus"
		set oDoc to front document
		set lstAllProjects to my ProjectList(oDoc)
	end tell
end run

on ProjectList(oParent)
	using terms from application "OmniFocus"
		tell oParent
			set lstProject to (sections where class is project)
			-- OR e.g.  (sections where class is project and flagged is true)
			
			if pfSkipHiddenFolders then
				set lstFolder to (sections where class is folder and hidden is false)
			else
				set lstFolder to (sections where class is folder)
			end if
			if length of lstFolder > 0 then
				return lstProject & my FolderProjects(lstFolder)
			else
				return lstProject
			end if
		end tell
	end using terms from
end ProjectList

on FolderProjects(lstFolder)
	set lstProject to {}
	repeat with oFolder in lstFolder
		set lstProject to lstProject & ProjectList(oFolder)
	end repeat
	return lstProject
end FolderProjects