Updated Framework Design Guidelines (markdown)

Framework-Design-Guidelines.md

@@ -35,6 +35,12 @@ Proposed Event rules for `Terminal.Gui` moving forward (STILL UP FOR DEBATE):
    - Subscribers of the event can do `theobject.EventToRaise+= (args) => {};` to subscribe.
    - Sub-classes of the class implementing `EventToRaise` can override `OnEventToRaise` as needed.
 
+
+Good article:
+
+https://www.codeproject.com/articles/20550/c-event-implementation-fundamentals-best-practices
+
+> In sum, a cancellable event is really two events and some activity that takes place between those events. The "pre-event" happens before the activity. The activity then takes place (or not). If the activity takes place, then the "post-event" is typically raised. So, to be precise, no event is being cancelled even though we say we have a cancellable event. Rather, the activity that takes place between the two events is what is cancelled — and likely prevented from starting at all.
 ## What needs to change for the project to adhere to the guidelines above:
 
 **UPDATE THIS AS THESE GET FIXED**