On the main window, I have "defs", "class" and "projects" docked on the left edge.
No other tool windows.
Open three editor tabs.
Float two of the editor tabs.
The floating windows get the "Standard" tool window layout, which includes "Open".
Select the main window editor again.
Menu: View->ToolWindows->Open
The "Open" tab closes on the 2nd floating window.
Menu: View->ToolWindows->Open again
The "Open" tab closes on the 1st floating window.
Menu: View->ToolWindows->Open - several times.
The "Open" tab opens and closes on the 1st floating window.
There is no way to get an "Open" window to open on the main window - except from the cmdline you can run 'applyLayout standard' - or the incredibly cumbersome right-click on a file tab in one of the floating windows, Duplicate "Open", then drag it to the main window.
In Slick 2013 the context menu you get when you right click in the title bar area of a tool window had "toolbars" and "toolwindows" menus.
Controlling which tool windows are open on which windows would be easier if the "toolwindow" context menu would come back.
