WE/2 beta 0.92mt exhibited a resurgence of the problem of beta 0.90, where any external viewer application must reside in a directory on the PATH in order to successfully execute. Beta 0.93 re-fixed this limitation, and it remains fixed in beta 0.94.
WE/2 beta 0.92mt introduced two external files, MAILCAP & EXTMAP, to allow the customization and extension/modification of the internal list of MIME types and external viewer associations. The MAILCAP file purports to allow the association of a more complex external viewer command with a given MIME type. This command can supposedly contain other parameters besides the input filename.
(For instance, "viewer -r %s" [Where "%s" is a placeholder for the input filename.])
Unfortunately, not only does this system not support commandline parameters which must follow the input filename, but any other parameters besides the filename are evidently being dropped. The MAILCAP parsing function in WE/2 does not properly separate the viewer name from the parameters in the command text, often trying to incorporate the parameters as part of the name of the viewer executable. WE/2 then complains that it can't locate the viewer "viewer.exe -r ".