[xubuntu-users] Xubuntu 17.04 and middle mouse button

[Jeffery Small]

I just upgraded from 16.10 to 17.04 and now have a serious problem with
my middle mouse button.

I use a Sun USB mouse with a standard 3-buttons and no scroll wheel.  In
16.10 and earlier I had normal control over the middle button and was
able to use it in all my programs as desired.  In particular, I use it
to control the All-in-One Gestures plug-in for the Firefox browser and
for various functions in a CAD program that I run under Windows-10 in an
QEMU/KVM session.

After the upgrade, all middle mouse button functionality is now lost --
including in the VM window!  It appears that either the the OS or Xfce4 is
hijacking the mouse and trying to implement drag scroll when the button is
pressed.  I can find no setting on the Window Manager, Keyboard or Mouse
and Touchpad settings menus to control this and haven't yet found any
documentation on this change.

I desperately need to restore the old behavior.  Can anyone suggest a
solution?  Thanks.
--
Jeff