procedure TNumEdit.WhenKeyPress(Sender: TObject; var Key: Char);
var
  p : integer;
begin
 case Key of
  '0'..'9'  : ;
  '.',','   : if AllowDec AND
                 (pos(DecimalSeparator,Text)=0)
                then  Key:=DecimalSeparator
                else  Key:=#0;
  #8        : ;
  #45       : if FAllowNeg then
                begin
                 p :=SelStart;
                 eValue:=-eValue;
                 if eValue>0
                  then  SelStart:=p-1
                  else  SelStart:=p+1;
                 Key:=#0;
                end;
  else        
    Key:=#0;
 end;
end;