How to install the advanced mate menu?

I just installed nixOS tonight, and have been trying to get comfortable with it

i’m going with the mate desktop

i installed a few new apps already using the rebuild thing… everything mostly works fine except the mate menu, which i am quite fond of from linux mint… i can’t get it to install

I added mate.mate-menu to the list of sys packages and it didn’t complain when it rebuilt, i even restarted X and restarted the computer and it doesn’t show any new panel applets to add the menu

This is what I was hoping to find:

I think its this package here:

which i already installed, without any issues. but again, its not showing in the panel applet list to add to the panel