Modal Popup Extender and flicker issues

ModalPopup extender is a very convenient and easy tool for designing lightbox style modal popups.

During development, I realized that the contents that go in the modal popup box appear for a split second when the page gets loaded. In repeated tries, I was actually able to grab a screen shot of the strange behaviour.

Look at the contents below the button! They are a part of the modal popup contents. Pretty weird, huh?

To get around this - simply set the popup panel's style to display:none.


And the modal popup extender code