This still applies to Roundup 1.4.2.

I can think of two possible solutions:

1) for XHTML output, check for templates with .xhtml extension first

2) provide conversion scripts to convert all templates from xhtml to html and vice versa, based e.g. on sgmllib.SGMLParser. A script could read the MAIN_TEMPLATES setting from config.ini and fix the templates accordingly.

I'd prefer the 2nd version, since otherwise several templates would need to be duplicated.