The following is a list of known issues with MATE on Slackware:

Tue Dec  3 12:12:18 UTC 2013
libgksu doesn't work anymore on Slackware 14.1 (and eventually -Current).
Possible workaround is to switch to root user using normal "su -" command.

Note:
We don't think there will be a solution for this problem as gksu and libgksu
are no longer maintained upstream. We will probably drop this in future
releases. This will also effect caja-extensions which has gksu modules in it.

Mon Jun 10 03:09:28 UTC 2013
If you are encountering problems with Caja (MATE's file manager) opening
directories when clicking on files in certain programs like Dropbox, Skype,
and others, the problem is that xdg-open (part of Slackware's xdg-utils
package) does not recognize the MATE desktop and therefore defaults to opening
the directories in Firefox.  Fixes for this have been committed to xdg-utils
upstream development in Git but for now, we must apply a patch to xdg-open and
add some xdg-mime default handlers.

First, as a root user, back up /usr/bin/xdg-open and then apply the
xdg-open.patch from msb/testing/xdg-utils:

patch -p0 /usr/bin/xdg-open < /location/of/xdg-open.patch

Then, as your regular user, first back up the following file:
$HOME/.local/share/applications/defaults.list and then enter the next two
commands in a terminal to set the default handler:

xdg-mime default caja-folder-handler.desktop inode/directory
xdg-mime default caja-folder-handler.desktop application/x-directory

You should be all set.  Thanks to Totoro-kun and T3slider for reporting and
discussing this in the LQ forums and also thanks to Giorgos Keramidas for
creating the initial patch.  Here is a link to the LQ thread which also has a
link to Giorgos's blog with the patch:

http://www.linuxquestions.org/questions/showthread.php?p=4968614

Wed Mar 27 04:23:24 UTC 2013
If you have dual monitor with NVidia card and set it up to use both monitors
as separate, you might encounter some freeze lockup.  A temporary workaround
is to change it into TwinView in your xorg.conf

Sun Mar 24 02:47:56 UTC 2013
If you run into strange panel issues, or missing icons, or theme problems,
please consider backing up or clearing out some of the hidden directories in
your $HOME, like $HOME/.config and $HOME/.cache and $HOME/.local.  If you
switch back and forth between different desktop environments, sometimes those
settings can get polluted.

Fri Mar 22 16:44:59 UTC 2013
Help menus and help buttons do not work -- this is a known issue per a MATE
upstream developer and scheduled to be fixed at some point but not in the next
release (1.6).

Fri Mar 22 16:43:36 UTC 2013
Working to determine whether mate-polkit is necessary.  According to upstream,
it is, although it results in duplicative polkit actions when a USB stick is
inserted, for example.  Disabling polkit-gnome in the "Startup Applications"
is a workaround until more testing is done.