Q:

Why is the PopupControlExtender generating a full postback inside an UpdatePanel?

I have a button inside an updatepanel. I have a PopupControlExtender linked to the button so when the button is clicked a panel pops up. It works fine except it does a full postback and I can't figure out why. The button and the PopupControlExtender is inside an update panel which inside the ContentTemplate tag. When I take out the PopupControlExtender the button only does a partial postback. I'm having trouble finding any useful information on the PopupControlExtender. Do I have to declare a postback trigger or something?
Edit: If I use a LinkButton control it generates a partial postback. Seems to only do the full postback with a Button control.

A:

Ensure the button's UseSubmitBehavior property is set to false

