I have found no way to add disabled options to a dropDownList from start directly (i knew with js code its possible).
It should be possible to generate the html code with the functions.
But therefore the code of listOptions in class CHtml must be changed.
The listdata shouldn't be used as a array of options instead it should be an array with 'value','disable' maybe also css class properties.
Another possibility could be to give the function an also a array of disabled options.
Whats your opinion?