[arch-general] Gnome-disk-utility (Gnome "Disks") problem

[Francis Gerund]

Hello.

I am running Arch up-to-date 64-bit, with Gnome desktop environment.  Until
recently, the Gnome-disk-utility (Gnome "Disks" program) was working fine.
The Gnome-disk-utility is currently 3.20.1-1, apparently updated
2016-04-12.

Today, when I start it using either the icon on the favorites menu on the
left side of the desktop, or from the catch-all icon on the favorites menu,
that goes to all of the icons that actually launch application programs in
Gnome, either way I just get the drop-down menu labeled "Disks" in the top
menu bar of the Gnome desktop.  No window appears for "Disks".

In the drop-down menu there are 4 choices:
1)  "Attach disk image"
2)  "Help"
3)  "About"
4)  "Quit"

Clicking Quit: the program never launches, the menu just goes away.
Clicking Help: the program never launches, but a Gnome Help window titled
"Disks & Storage" does pop up.
Clicking About: -nothing happens.

Clicking "Attach disk image" just the far left part of a window pops up,
the rest of the window is past the right edge of the desktop.  The window
is titled "Select Disk Image To Attach".  It looks like a window from Gnome
"Files" (Nautilus).  Clicking "Cancel" makes that window go away, revealing
the main "Disks" window, which *seems* to work as usual, but I am reluctant
to test it out.  Clicking the "X" buttion dismisses the window, as
expected.

(Note: at times investigating this, the gnome-disk-utility window(s) may
lock up, as well as the mouse, requiring the entire desktop to be "crashed"
manually using alt-ctl-bksp, to escape.)

I have, in various combinations,
1) rebooted
2) updated (sudo pacman -Syyuv)
3) reinstalled gnome-disk-utility (sudo pacman -Rs gnome-disk-utility)
4) downgraded using the local package cache to the previous version,and the
the version before that (sudo pacman -U
gnome-disk-utility-3.20.0-1-x86_64.pkg.tar.xz, and sudo pacman -U
gnome-disk-utility-3.18.3.1-1-x86_64.pkg.tar.xz)
5) upgraded gnome-disks-utility again (sudo pacman -U
gnome-disk-utility-3.20.1-1-x86_64.pkg.tar.xz)
6) searched online for information
7) told the problem it was not wanted here and to please go away.

The problem did not go away.

Note: part way through the process, gnome-terminal suddenly showed the same
problem, which went away as soon as gnome-terminal was reinstalled. So I
suspect that the problem may not be with gnome-desktop utility, but with
something else, perhaps recently updated, in the Gnome system.

I did rely upon gnome-disk-utility, especially to manage external usb disks
without losing data,  so this is a real problem.

Has anyone else run into this problem?

Any solutions?  Any ideas?