DefaultGroupExpanded doesn't allow separate padding setting for top, left, bottom, and right.

[jeff-phillips-18]

Describe the problem
The DefaultGroupExpanded uses the largest padding set for the padding style on the element. The padding field allows for separate settings for each (like setting paddings in css) but it uses the max value if the value is not a simple number.

In order to prevent label overlap the bottom padding is needed to be greater but that creates unnecessary padding on the top, left and right.

How do you reproduce the problem?
Set the group element padding to [15, 15, 75, 15]

Expected behavior
The group's padding should be 75px only on the bottom, the rest should be 15.

Screenshots

[jeff-phillips-18]

/cc @leandroberetta

[jeff-phillips-18]

The padding is correct for rectangular groups but not when the group uses the hulled outline. Fixing the hulled outline seems to be a rather large task. I'm not sure it's worth the effort unless there is a project that really needs it. I'm going to back-burner this issue.