Ensure that this popup window is not maximised (or tab, in the case of tabs being rendered as an MDI).
Ensure that your browser settings allow browser windows to be moved by scripts.
Press your mouse down on this text but do not move it afterwards. Fail if a drag operation has started (eg. if the mouse cursor shows that you are dragging something, or if some drag placeholder text appears, or if this text changes).
Press your mouse down on this text but do not move it afterwards. Fail if a drag operation has started (eg. if the mouse cursor shows that you are dragging something, or if some drag placeholder text appears, or if this text changes).