You can float Slate Material Editor windows, except for the View.
To float a window such as the Material/Map Browser, Navigator, or Parameter Editor:
To dock a floating window in its default location:
3ds Max docks the window back in its default location, as shown in the illustration above.
By default, each Preview window opens as a floating window. When you dock a Preview window, it docks at the upper left of the Slate Material Editor dialog.