GNU/Linux Desktop Survival Guide
by Graham Williams
Out of Date Toolbars (and menubars) can float. The left end of each toolbar and menubar contains a raised dotted image like that above. By placing the mouse over it and holding the left mouse button down you can drag the toolbar to wherever you like before releasing the mouse button.
Unlike floating (or tear-off) menus a floating toolbar or menubar does not remain in the main window. You will have at most just a single instance of a toolbar.
A toolbar or menubar can be returned to the parent window simply by dragging it back there. You can even drag the toolbars to the bottom of the parent window if that's where you like them to be.