When this forum is approached from http://cesiumjs.org/forum.html and you try to make a link all the link does is take you to the main forum page, not the topic. If you look at the console you’ll see an error like this:
Invalid ‘X-Frame-Options’ header encountered when loading ‘https://groups.google.com/forum/embed/?place=forum/cesium-dev&showsearch=tr…=true&hideforumtitle=true&parenturl=http%3A%2F%2Fcesiumjs.org%2Fforum.html’: ‘ALLOW-FROM http://cesiumjs.org’ is not a recognized directive. The header will be ignored.
If you approach this forum from https://groups.google.com/forum/#!forum/cesium-dev the links work just fine.
So until this is fixed, if making links is important it’s probably best to use the groups.google.com domain for the forums.