The pinch-zoom feature has been temporarily disabled in 1f5d683e6bbab6d5694bd28524b24022fef70195, as a side-effect of fixing the extremely slow two-finger-drag (at least on Mac OS X), see bug #1056. We should investigate how we can have correctly working pinch-zoom as well as a usable/fast two-finger-drag on Mac OS X (possibly other OSes?). This may or may not involve the unfinished proposed patch from here: https://sigrok.org/bugzilla/show_bug.cgi?id=1056#c12