Qt Creator has a nice feature: in the Tabbar menu (the one where the split actions reside) the user can select "Open in New Window" which opens the file in a window where all Tool Views and the main menu are removed. This is useful when concentration on one file is needed. Also, maximizing this "one file window" maximizes the available space to view the file. Also, it can be easily moved to a separate screen.
I like it!
Did you try View -> New Window in Kate? it should: "Create a new Kate view (a new window with the same document list". Nice feature, works for me (instead of implementing a "open in new window" menu action for the document list tool view). YMMV.
We have now the 'detach document' entry, in 23.04 that will give you a new window with just that document.