Ajax modal popup inside update panel causes flickering

I have an ajax modal popup, which is shown on click of a button in base page.

And on click of a button in popup, Base page should be updated. Everything works perfectly fine.

But the popup f开发者_开发问答lickers on click of the button in base page. Please help me to avoid this flickering effect.

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Put everything inside the modal popup's panel in a update panel.