Font in AdvStringGrid

I try to change the header (first fixed row) in my DBAdvGrid but I don't understand how to change the font.
When I try to change the font  (Font.color or FixedFont.Color) properties in the example asg5 it doesn't work. Is there a property to disable for it like systemfont ?
Another question : what is the FixedColor utility ?

You can use either the event OnGetCellColor or grid.Columns[colindex].HeaderFont

Thanks Bruno i use the 2nd solution and it is OK.

So what are the FixedFont & FIxedColor properties uses ?