The Windows->Twin menu item restores the twin Files window style. Any user rearrangement or size changes are retained. This window style is automatically set when comparing directories using the Compare dialog. Rearrangement is discouraged for this reason.
The default twin window arrangement is two equally sized windows, similar to vertically tiled windows, that occupy all the center window area of the FS/2 main window. This style is good for viewing files in the Details view or visual comparison. However, the windows obscure the Drive and Directories windows. To restore the Drive and Directories windows on top, push F5 or F6 respectively. Then click in the current Files window (or use F7/F8) to again put the Files window on top when finished with the Drive or Directories windows.
You must select another window style to exit the twin window style except when using the Compare dialog. Use the window style 'Ring' pushbutton in the lower left corner of each Files window to toggle the window style to next/last style or use the Alt 1 through 4 keys to select the desired style. A 'Last' window style pushbutton may also be configured in the Toolbar or use Ctrl+Backspace to toggle between two window styles.
Accelerator Keys - Alt 5
Example of Twin File Windows