Script custom action notes

Unsorted notes related to VBScript and JScript custom actions (assuming the world can’t talk you out of it):

• Use CreateObject, not WScript.CreateObject.
• Use Session.Property (or just plain Property) to get and set properties from a custom action:
  ' VBScript:
Session.Property("USERNAME") = "Valued Customer" ' value must be a string
MsgBox "Hello, " & Session.Property("USERNAME")
• For Directory-table properties, use Session.TargetPath("CaseSensitivePropertyName")
• Session.Property in a deferred custom action requires use of CustomActionData.
• If you want to catch the return value from a script function, the script code must be stored in a file, and not in the CustomAction table.
• Script custom actions cannot be run asynchronously. (I found this out only recently when I was experimenting with SpawnWaitDialog, about which more later.)