Panes are docked by default within the editor window, but some tasks may be easier if you float a pane. A floating pane can be moved outside the editor’s window.
When you open another editor If you have a floating pane in the editor and then open another editor, the floating pane temporarily disappears. It reappears when the original editor is selected.
To float a view in its own pane:
Select Float from the title bar’s pop-up menu.
To float a view in a stacked pane:
Select Float from the tab’s pop-up menu.
To dock a floating view:
Select Dock from the title bar’s pop-up menu.