FYI I've also tried placing the TMSFMXWebGMap control on a blank form. The blank gap is still visible at the top of the form.
As an experiment I added this code to a button onclick event:
begin
TMSFMXWebGMaps1.Visible := True;
TMSFMXWebGMaps1.Position.X := 0;
TMSFMXWebGMaps1.Position.Y := -20;
end;
The map still shows at the position about 20 pixels down from the top of the form.
I'm thinking that I'm simply missing some small option or feature. Any ideas?