The Windows->Custom menu item restores the custom file window style. Any user rearrangement or size changes are retained.
The default custom window arrangement is one where the active Files window partially obscures the recessive Files window as shown. Activating the recessive Files window brings it to the foreground. However, the size and position of the active and inactive windows is constant, regardless of which window is active. When the recessive Files window is activated, it is automatically resized to the active size and placed in the foreground, while the previously active window is automatically resized to the recessive size and placed in the background.
To reset the windows to default size and position, push the Size pushbutton in the Data Panel.
This arrangement is good for all window views. It is not good for visual comparison of the content of the two Files windows.
Accelerator Keys - Alt 4
Example of Custom File Windows