My understanding is that this bug is known to be present in MATE 1.8, 
but will be fixed in the next release:
   http://forums.mate-desktop.org/viewtopic.php?f=2&t=3274

Meanwhile, there is a workaround using dconf-editor:
 
http://forums.mate-desktop.org/viewtopic.php?f=2&t=3274&sid=e98780617c56d376cadbc4c1af5f14e7&start=10#p10348

Cheers
Ben

On 04/12/14 05:29, Yasha Karant wrote:
> I understand that this is not an EPEL list.  However, Mate is an EPEL
> port to EL7.   I have been attempting to use Gnome 3, both Classic as
> well as Frippery; but I find that Gnome 3 lacks specific functionalities
> that I prefer.  Evidently, Mate is a port/clone of Gnome 2 for
> distributions using Gnome 3, including EL7.  I have installed Mate 1.8.1
> as well as the applets, etc., from the EPEL list in the Add/Remove
> Software GUI.
>
> However, the window selector grid has a fixed 4 windows, and the right
> click Preferences on the selector does not allow me to increase the
> number of workspaces.  A search on the web reveals that this is
> supposedly fixed in Mate 1.8 , but is not on my machine. Does anyone
> have a solution?
>
> Supposedly Oracle EL 7 uses Gnome 2.  Is it possible to use the Oracle
> EL 7 rpms to install Gnome 2?
>
> Yasha Karant

-- 
Dr Ben Waugh                                   Tel. +44 (0)20 7679 7223
Computing and IT Manager                       Internal: 37223
Dept of Physics and Astronomy
University College London
London WC1E 6BT