Unnecessary close button on floating tool windows

Hello, it's been a few years but if I recall correctly, there might have been problems with either the toggling itself or knowing when to toggle the close button (which is rendered by the Windows system) after various docking operations occur.  There are scenarios where you might start off with a single tool window that can't close.  But then another tool window could be docked into or next to it that does allow closing, and the close button visibility would need to be based on what is currently visible/selected.  I don't recall the exact issue but I believe we ran into problems in the past when trying to add this functionality.  So at the current time, we disable closing (when the close button is clicked) in scenarios where it isn't appropriate to be allowed.