It would be nice to have thumbnail size scaling, like pcmanfm does.
Thunar already has thumbnail scaling via the context menu or holding CTRL and +/-. The problem is that it doesn't let you scale the thumbnails large enough to be properly visible on 4K+ displays, hence I'm just about to create a ticket for that issue.
There was no need for me to create a new ticket, someone had beat me to it: https://bugzilla.xfce.org/show_bug.cgi?id=14057
Closed in favor of Bug #14451, since #14451 provides much more details (and now as well a patch ) *** This bug has been marked as a duplicate of bug 14451 ***