Hi Fabio.

This is possible, but I uses context menu,
and this solution remove the listbutton from the zone available in order to open it.

Hmmm. Why a context sensitive menu on a drop down list? Perhaps there is a different, more intuitive way, to accomplish what you are trying to do.

Not acceptable for my standards of programming.

< lol >!!!! Now, if English were your native language, I would probably be insulted by that remark because the obvious implication is that your programming standards are much higher than mine ( and apparently than anyone else's ).

Since English is not your native language, I will assume that this is not what you meant to say < s >.

I have found a workaround, but it require to store a flag,
>and i don't love workaround flags ( a source of hidden side bugs ).

Please let me know when you have found the programming language that does not require any workarounds and that has no idiosyncracies.

First my rule:
not to use the normal roads that use all, why a lot probably they works.

When I write applications for my clients, I program to the 90% use case. IMHO, if all you do is program to the exceptions, nothing gets done.