I need to make a custom control and decided, before that, to see if there were any additional components that I could utilize.

When looking through the list, I found a component called an Expander. So I decided to add it and see how it works.

After adding it, I couldn't find it at all within the toolbox. I went back to Choose Items and it was checked, but still not in the toolbox.

It's probably important to note that it is a WPF component and this is not a WPF Project. Would that make a difference?

Is there something else I may be doing wrong?