The related widget css has some rules that match any tag with the edit class and the Products.Collage compose form has a div with the edit class. This screws up the rendering of the form. The selectors for the rules in the related widget css should be changed so that they only apply to the edit links in the widget an not every tag with the edit class.
To reproduce this install both Products.Collage and collective.z3cform.widgets in the same Plone site, create a Collage and then go to the compose tab.
The related widget css has some rules that match any tag with the edit class and the Products.Collage compose form has a div with the edit class. This screws up the rendering of the form. The selectors for the rules in the related widget css should be changed so that they only apply to the edit links in the widget an not every tag with the edit class.
To reproduce this install both Products.Collage and collective.z3cform.widgets in the same Plone site, create a Collage and then go to the compose tab.