Adding custom picture frames - how?

I recently pasted an imageholder from the "Graph Paper" theme into another presentation and it brought with it a custom picture frame. When I select the imageholder the custom picture frame appears in the "stroke" part of the property inspector as an additional picture frame type (i.e. in addition to the ones normally present). But if I change the frame to one of the normal picture frame types the 'extra' frame disappears.

Is there a way to create and save such 'custom' frames so that they can be re-used again?