Would be handy if double clicking a script executes it (in Script manager panel).
It does.
Double-click on the script name (not the icon) to run a script.
Hold down <Alt> and double-click to edit, <Shift> + double-click to edit the properties.
Well - it does not work with all scripts. Have not been able to figure out what is the difference.
I suspect if the script opens up an input panel it fails.
Example to test: John Zeman's Caption editor or his category jumper script.
When you double-click a script manger node, it launches the script. The script is not running at the time so it cannot effect how the script manager works.