nate@Dad:~$ xmms
/usr/share/themes/Breeze/gtk-2.0/gtkrc:4: error: unexpected identifier `gtk-color-scheme', expected keyword - e.g. `style'
/home/nate/.config/gtkrc:5: error: unexpected identifier `gtk-theme-name', expected keyword - e.g. `style'

** CRITICAL **: setup_ctrlsocket(): Failed to assign /tmp/xmms_nate.0 to a socket (Error: Permission denied)

From my system:
it launches just fine. Do you have any custom GTK themes set? That error message suggests there's an issue with the theme itself so knowing which one you are using would be helpful.

no not really im using current added yesterday

I think maybe Cinnamon and Gnome 3.38 is conflicting with XMMS theme?
root@Dad:/home/nate# slackpkg file-search gtkrc

Looking for gtkrc in package list. Please wait... DONE

The list below shows the packages that contains "gtkrc" file.

[inst] cinnamon : mint-themes-1.8.7-noarch-1_csb
[inst] gnome : gtksourceview-4.8.1-x86_64-1dl
[inst] multilib : gtk+3-compat32-3.24.30-x86_64-1compat32
[inst] slackware64 : Greybird-3.22.15-noarch-1
[inst] slackware64 : breeze-gtk-5.23.0-x86_64-1
[inst] slackware64 : gimp-2.10.28-x86_64-1
[inst] slackware64 : gnome-themes-extra-3.28-x86_64-3
[inst] slackware64 : gtk+-1.2.10-x86_64-9
[inst] slackware64 : gtk+2-2.24.33-x86_64-2
[inst] slackware64 : gtk+3-3.24.30-x86_64-1
[inst] slackware64 : gtksourceview3-3.24.11-x86_64-4
[inst] slackware64 : oxygen-gtk2-1.4.6-x86_64-4
[inst] slackware64 : pidgin-2.14.8-x86_64-1
[inst] slackware64 : pygtk-2.24.0-x86_64-7
[inst] slackware64 : thunar-4.16.10-x86_64-1
[inst] slackware64 : vim-8.2.3487-x86_64-1
[unin] alienbob : rawtherapee-4.0.8-x86_64-1alien
[unin] mate : gtk-engines-2.21.0-x86_64-1_msb
[unin] mate : gtksourceview4-4.8.1-x86_64-1_msb
[unin] mate : mate-themes-3.22.22-noarch-1_msb
[unin] slackware64 : xfwm4-4.16.1-x86_64-3

You can search specific packages using "slackpkg search package".

So this is KDE? Which theme do you have set for GTK applications?
go to Settings->Appearance->Application Style->Configure Gnome/GTK Application style.

Oh that could be. The error says you are using Breeze which ships with plasma but maybe something else is getting pulled in.

Ya Im using Breeze.
I really think it has to do with having multiple DE's on my system....
Hum i think I mite have to delete some.

Attached Thumbnails

 

I'm not very well versed in how the themes are pulled in but there is a load order so it's probably pulling in the wrong breeze or something.

Ya i do see what you are saying cause I just found out I have 3 different gtk's installed on my system gtk 2.0 gtk 3.0 and gtk 4.0

That's normal but due to all the other stuff you installed it could be a version mismatch. The theme engine is giving that error so it could be a compatibility error. On my system xmms is compiled against gtk 1.2. Maybe see if you can reproduce this in a different desktop or in fluxbox.

EDIT: also make sure you have all 4 GTK packages installed...
slackpkg search gtk

Hi

Check the environment variable GTK_RC_FILES.
$ echo $ GTK_RC_FILES
or
$ export

In my current Slackware, this variable is set to "/etc/gtk/gtkrc:/home/user/.gtkrc:/home/user/.config/gtkrc"
//user - your user on the system

GTK1 theme settings are set by default in /etс/gtk/gtkrc

In your case, this variable is most likely set to the GTK2 config file ....