Page is getting refreshed after closing new window which was opened from the main page

I have a page where in I have a grid control with Image button as one othe ItemFiled. When I click on the image in any binded row, I am opening one new window which is again a aspx page. The problem is when I close the new window, the page from where the button is clicked is getting refresh, which is not required for me. It should be in 开发者_JS百科it's state and should not be refreshed.

Can anyone help me here?

Thanks in advance

In ImageButton: OnClientClick="return showPopup();"

Add at the end of showPopup function: return false;