Let's see if I can help any ...
I hadn't updated my Xfce box in a while, so I first created a desktop icon/launcher to launch Firefox. (I typically don't have any, since it reminds me so much of MS Windows, where EVERY program wants to claim a piece of your desktop real estate). I wanted to insure that the launcher worked prior to updating and rebooting, which it does.
Now, I'm applying my updates (all 417 packages). Once it finishes, I'll reboot.
On a side note, the permissions for the .desktop launcher file on the desktop for Firefox (that I just created) is NOT set up to be executable. The permissions are for me (as the user) to have read & write access, and all other groups and users to have read access.
I also did a quick look at the files being updated, and I'm not seeing any Xfce files being updated that should affect launchers on the desktop.
I'll update this after I have finished the updates and rebooted.