Close button "X" is highlighted

Hi,
I am able to click(push) the close button "X" even if i disable it using Disable(CANCELBUTTON) in setup progress screen which is enabled using Enable(STATUSEX). It is an installscript project. Is there any way that the user will not be able to click the close button "X" if it is disabled which is correctly working with Cancel button. Is the any way to get the handle of the close button "X" alone.