Doing tutorials and how do i fix this

When i do the GUI tutorial everything working except for the window closeing when i click on the x to close the window the tutorial says its suposed to close has this been changed or is it a bug and if its a bug then how do i fix it

in case the person answering this does not know about the GUI tutorial it has you make a button and when you click on it a window appears this window is suppose to be able to close if the can close field is checked which it is