lambo,
when you say soft buttons - do you mean the buttons are rubber ( or a different type of plastic ? ) and you need to subsequently bond these to hard plastic ?
either way, think this glue may help since the problem in the past is getting any glue to work on the PP range of plastics, but this stuff
is still a cyanacrolate super glue but supplied with a primer for the hard plastics issue. So i would have thought it would do the trick of bonding even dissimiliar materials.
cheers, Nick.