B is controlled by element "HeaderBar" and defaults to "Panel.ChildHeader.Default" if not provided
i dont have time to check but would guess C is controlled by "Panel.ChildHeader.Default"
Ok, I hope I got all this right:
1:
When ignoring any overules I believe that:
A and C are both controlled by:
id="Content[TrackDetail].Body.Default" bdr=
B and D are both controled by:
id="Panel.ChildHeader.Default" bdr=
I can't oversee possible other implications, but looking at the screenshot for this skin, I feel it would make more sense to have C follow B and D.

2:
Two observations about the "HeaderBar" element:
fg= doesn't do anything?
And a visual error:
When I set the element, the title bar looses it's bitmap color and becomes plain white:

3:
I believe I might also succeed in what I am trying to achieve with using the existing id="FilterPanel. elements.
But they currently don't seem to work at all for v3?