Change selector for spaces dashboard integration

Issue Summary

Hi,

I have done new custom boxes extending the boxes_box class and declaring it in to the boxes_boxes_plugin hook.

The problem is that I'm trying to change the option list where this box are displayed in the "customize dashbord" tool. I tryed changing the 'parent' element in boxes_boxes_plugin but it doesn't work.

Me be a bug? me be not documented issue?

thanks for advance