Some windows in LibreOffice are dockable, such as the Navigator window. You can move these windows, re-size them or dock them to an edge.
Docking and Undocking Windows
To dock a window, do one of the following:
Drag the window by its title bar to the side, or
Double-click inside a vacant area of the window while holding down the CommandCtrl key. In the Styles window, double-click a gray part of the window next to the icons while holding down the CommandCtrl key. Alternatively, press CommandCtrl+Shift+F10.
These methods can also be used to undock a currently docked window.
Showing and Hiding Docked Windows
Click the button on the edge of the docked window to show or hide the docked window. The AutoHide function allows you to temporarily show a hidden window by clicking on its edge. When you click in the document, the docked window hides again.