Window | Dock All
Click Dock All on the Window menu to dock all of the floating windows, except for those with Always floating selected on their shortcut menus.
WinDbg automatically positions each floating window. If a window has never been docked before, WinDbg moves it to a new untabbed location. If a window has been docked before, WinDbg moves it to its most recent docking location, which might be either tabbed or untabbed.
For more information about docked, tabbed, and floating windows, see Positioning the Windows.