Exactly...........that's what Shift+F11 should open.............The Uniform Dialog Box.
I was sending you there to make sure that we were talking about the same palette.
(You can navigate to the same place going to Window, Color Palettes, Color Palette Browser.) Just thought it was better for you to check the palette out before you opened it on your workspace. Doesn't matter, either way.
Anyway, back to the Uniform Fill Dialog box. Go there and follow these steps:
Along the top, you'll see 3 tabs. Choose Palettes. It will be the 3rd choice on the right.
In the drop down, choose Users Palettes.
Then choose Custom Spot Colors.
You can now look at the palette, scroll thru it and see if this is what you were looking for.
It's a fairly large palette in X3, but you can edit it to include/exclude any colors you want. Just make sure you start by renaming it.
If you're still confused, let me know.