Pop up position always reposition to "window" when resize the window

Pop up position always reposition to "window" when resize the window

Hello,
 I use the popup widget of jqm1.4.2, set data-position-to="#position-header ", but when open the popup div then resize the browser window, the div is reposition to the center of window position not the original one. I check the code of the jqm1.4.2 there is something as follows: