I was thinking a bit and rather than put the code in the textbox refresh, I could be better in the value_assign, like:

LPARAMETERS vNewVal
*To do: Modify this routine for the Assign method
THIS.Value = m.vNewVal
IF VARTYPE(this.value)="N"
this.forecolor = IIF(this.value<0,RGB(255,0,0),0)
this.disabledforecolor = IIF(this.value<0,RGB(255,0,0),0)
ENDIF

I think that with this, every time the value of the textbox changes his value, I get proper coloring, rather in the refresh that I must call it explicity via a thisform.refresh() o thisform.mytextbox.refresh().

What's your oppinion?