checkboxes in f21 gnome apps

[Stuart McGraw]

I just installed Fedora-21 and xfce.  Install was from
the regular live x64 download, not the xfce spin.

I have an odd problem with checkboxes in gui dialogs:
they don't show any checkmarks.  If I click on a
checkbox, a checkmark will appear for a fraction of
a second then disappear.  From the program's behavior
I can tell that the setting got set but it is obviously
difficult if one can not see which boxes are checked
in a dialog and which aren't.

This problem seems to be limited to Gnome apps (the ones
with the new -- at least to someone coming from F15 --
and really unpleasant UI design).  For example, brasero
exhibits the effect but k3b doesn't.

Does this problem ring a bell with anyone?