First, it would be much better to use metric trace widths when routing metric pitch BGA's.
10 mil = 0.25mm
8 mil = 0.2mm
6 mil = 0.15mm
4 mil - 0.1mm
To see the real trace width you need to use the modeless comand "R" for "Real Width".
Type R1 <enter> and every size above 1 mil will display its Real Width and everythng below 1 mil will show as a thin wire.
Thanks Tom for the answer, it works fine and makes the layout more convenient.
M Y Abdulghany
Thank you very much !