Allowed component is part of design. Make sure to configure the property "components" as type string with list of all the components. As an example for geometrixx you can refer .
From firebug console what is the error you are getting when you checked and save from felix console?
Thanks, I was expecting to define this on the Template but you are completely right, it is the Designer in /etc/designs. One thing I noticed that I want to point out to people is that when I edit a New Page instance in Design View, click Edit on a par, that it does in fact create this property "components" on the par inside /etc/designs/ourdesign, but it uses type String instead of String Multi. So I deleted the scalar "components" and remade a new array "components" property with String Multi.
Instead of being created under "/etc/designs/mydesign", mine was created under "/etc/designs/default/jcr:content" when I enabled (check the boxes) the "Allowed Components" in the Edit of my "par" in the Design Mode. Why is this so?