How can I refresh with gCLS only a part of the screen and not the whole screen ?
gCLS Question
As far as I know, you can't, but you can simulate it with gFILL:
gAT left%,top%
gFILL width%,height%,1 REM 1 clears the area
It's not possible. Besides the gFILL solution from Arjen I would suggest using more than one window.
Martin