Gui - notifyflags

Hi,

Have spent a few weeks trying to learn about Gui, despite going through posts at the forum, searching on the net - very little in the beta updates, I have been unable to understand the use of as well as how to use the following :-

2 - setfocus (all)*
4 - killfocus (all)*
16 - edit change (edit)*

Thankful if some of the old masters can explain the same with simple examples.