It looks like this filechooser issue - as far as I can see is mainly related to zenity.
Furthermore trying to reproduce it on exactly same fresh Linux installations - once installed on Parallels Desktop and once installed on VMware gives different results.
My actual investigations based on installations using my descriptions in this thread gives in a reproducible way the following results :
On Parallels Desktop 11 on Mac OSX hosted (El Capitan):
Ubuntu 14.04 (zenity 3.8.0), 16.04 beta2 (zenity 3.18.1.1) , elemtary OS 0.3.2, Mint 1.7, Fedora 23 (zenity 3.18.1.1)
->no issues at all everything works without freezes
On VMware as well as on VirtualBox, independent if hosted on Windows 10 64bit or Mac OS X (El Captian) the newer zenity versions freezes, that means Ubuntu 16.04 freezes, Fedora 23 freezes.
My actual assumption is, that the newer zenity version 3.18.1.1 interferes somehow with the VMWare as well as Virtual Box approaches of interacting between host and guest filesystem (their kernel modules, e.g. for copy & paste between host and guest file system etc. ) - but this is actually just a guess, I’m drilling it further down.