Create a supertype with a name field. Create a subtype of it, also with a 
name field. The subtype now has two name fields, one inherited, and one 
not. Now delete the name field which is not inherited.

Before the deletion the right-most button for the two fields is ">>" for 
one, and "-" for the other. Pressing the "-" removes the non-inherited 
name field, but the button of the other field then changes from ">>" to 
"-". Reloading the page makes the remaining field display correctly.