MacroView DMF 9.1 and later has added support for changing the position of the preview screen in DMF explorer and Outlook independently.

Setting can be see in the Appearance pane of the User options. 

The document preview pane displayed below the file list in MacroView DMF and MacroView Message can be toggled on or off when required so that there is more screen real estate available for the file list.  MacroView DMF 8.4 or later also allows you to position the preview pane to the right of the file list which can be particularly useful with the wide screen monitors.

Turn preview pane on or off

To toggle the preview on or off in DMF Explorer, click the preview button in the bottom right corner of the window. 

To toggle the DMF preview on or off in Outlook, select the Hide Preview Pane or Show Preview Pane option on the Current View menu in the MacroView group on the home ribbon. 

Changing the preview pane position

The preview pane can be located below or to the right of the file list in Outlook and DMF Explorer.

To change the position of the document preview pane, select the required location under Options > Office > Preview Pane Location