First of all - sorry - I've overseen that there is already a post about "Enabled=false" does not work.
By the way - in IE8 it works for me :)
Anyhow - i threatened to provide an example :) and so I did.
And I found out that there is no section for the ListBox in the Code Library.
But (in this case) this doesn't matter - since simply showing databinding and "Items access" on postbacks / callbacks looked boring I made an integration sample where I use 2 RadListBoxes in a RadGrid to show / edit option sets.
A soon as the sample has passed screening you will find it under "General and Integration Projects"
Anyhow - the Listbox is great - maybe someone could open a section for it in the Code Library.
Maybe we will soon find samples there :)