Using Select[multiple] with ctrl/shit

Hi Allan,

We have select input fields which are multiple selection.
The problem is that the users has only two options:
1. Select one option.
2. Select several options in a row while holding the mouse button.

The problem is that some time you want to choose options that are not successive (A,C not A,B,C).
In other multi-select fields we know you can use the ctrl to do that, how can we achieve it in the Editor?

Thanks,
Yishay