Apple Final Cut Pro 5 - Manual (Page 51)

50 Part II Learning About the Final Cut Pro Interface
To make a tab appear in its own window:
m Drag the tab out of its parent window (Browser, Viewer, Canvas, or Timeline).
To put a tab back in its original window:
m Drag the tab to the title bar of its parent window.
Moving Windows
There are several ways you can move windows in Final Cut Pro. You can move a
window by clicking its title bar, and then dragging it to a new position and releasing
mouse. You can also hold down the Command and Option keys, and then click
anywhere in a window and drag it to a new position.
The Effects tab is dragged
out of the Browser and
appears in its own window.
Drag the tab
to the title bar of the
original window
to put it back.