Hi Xavier,
Yes ! You're right ! This option for mobile purposes have not been built in for the LIST BOX component.. And even in 1.6 we didn't have any improvement regd this functionality in List Box Component. So you'll have to use scripts, but you need not use Scripts in another button, but use the script in the List Box - On Select .. Refer my Blig on this, whose link has been shared by Tammy in the above Comment. That would help your scenario perfectly !
Thanks
Gowtham S