Any window with a title bar can be dragged into a floating position or be docked. When dragged the window's potential position is shown as a square "rubber band", and if you let go of the left mouse button, the window will take this position. If the cursor is over a docking icon (circled in illustration), the window will be docked, unless the icon is ghosted (greyed out).
To make a window floating, avoid releasing it over a docking icon.
The tab icon in the middle of this cross
docks the window behind another docked
window, accessible by a tab.
Clicking the pin into a vertical position will hide
a docked window behind a tabbed border each time the
cursor is moved away from it.