Webmin 1.340 on Slackware 10.2, Firefox 2 for Windows browser. Apache 2.2.3, non-default apache configuration file.
This appears to have broken since the last release.
On creation of a new virtualhost or when setting "Virtual Server Details", the Apache module does not accept a non-default port number. It can be set using the "Edit Directives", and then will be *read* by Webmin correctly, but still cannot be changed through the Port Number field.