Forum container should not be a selection choice from drop-down in create forum topic

I believe that being able to select a container from the drop down list actually a bug since doing so returns an error message.

I think that showing the containers makes user life easier locating the desired forum where he/she wants the topic to be placed, so IMHO hiding the containers from the option list is not a possible solution.

What would you expect to happen if you select a container as the forum instead of the error? Or how do you think that the forums available should be displayed to the user?

Showing the container in the drop down list is a good thing, being able to select it is not. I re-titled this issue.

One possible way of achieving this is adding to the markup of the option the attribute "disabled".

However, the Forms API doesn't support this, and this solutions seems to not work in older versions of IE.

Adding tag "dlatino" for reference of the Drupal Latino community.

One could specify the containers as optgroups and is supported by the form api by doing nested arrays in #options. I'll work on a patch soon if time permits. This would be easy for a novice to do.

Here is relative issue about optgroups:
#1407746: Support grouping in select list for term reference field

There's issue already #12089: Better method of showing forum containers in form