Revert "GroupWidget: Fix messy inheritance chain"

It turns out I completely misunderstood what this class is
all about. Will put in a followup commit that explains what's
going on.

This reverts commit 98c9d049d4b9f0ec2043504732cc57f0db62df43.

Change-Id: If53b55a96c37f822955e080b966c34317c382340