FoxPro/Visual FoxPro - Define Class

Hola
Tengo el siguiente codigo

define class form1 as form
pstring = ''
add object grid1 as grid with ;
top=200, ;
left=100, ;
columncount = fcount('tmppas') ,;
deletemark = .f. ,;
recordsource = 'tmppas'
recordsourcetype = 1

procedure grid1.init
for i = 1 to fcount('tmppas')
this.columns(i).controlsource = field(i)
this.columns(i).header1.caption = field(i)
this.columns(i).readonly = .t.
this.column1.width = 300
endfor

este funciona
procedure grid1.afterrowcolchange
lparameters nColIndex
thisform.txt1.value = tmppas.usuario

Pregunta
tengo la sigueinte instruccion y no anda
esta bien definido elmetdo interactivechange ya que lo debague y no entra nuca aca
puedo definir comoprocedimiento este metodo, esta buien aplicado ??

procedure grid1.column1.interactivechaneg
sele tmppas
thisform.pstring = thisform.pstring+chr(lastkey())
locate for upper(alltrim(usuario))=upper(alltrim(thisform.pstring))
thisform.grid1.refresh()

enddefine