Thanks for the post with pics....
you wouldn't even know there was a center engine component closing panel....cause the whole thing just disintegrates as you suggested!
And the windshield frame cover (alias cowling flashing ) is actually the bottom seal or cover that the Windshield Moulding Trim Seal for Front Windshield (the subject of another DIY) attaches to. I noticed this piece was chipping away there at the bottom of the wondshield just like it was at the top!
Good catch on your part.
I haven't really experienced any problems as a result of this deterioration / disintegration (that I am aware of) but still want it to be fixed. BMW really screwed up their materials selection for this stuff.
This topic should be a sticky because this will happen to every e39 I bet.
The man in the boat!