PillarSoft

http://www.pillarsoft.net/help/os2/warp-zip/viewers.shtml

WarpZip online help - Viewers

The View button and menu items will use the internal viewer whenever possible but changes can be made to viewer behavior when double clicking a file to view.

There are three choices for the text and graphics viewers:

Clicking on the "External" radio button opens a file dialog to locate the viewer you wish to use and automatically enters it's name in the viewer field.

Unzip Settings  WarpZip AntiVirus