>In a modal form I have two commands button:
>in the first one i have a do while loop inside this i write a txt file.
>in the second one i try to cancel the loop process and close the form.
>The problem is that i can´t click in the second button (to cancel the loop process) until the loop is finished.
>Can you help me ?
>Thanks.

Add DOEVENTS() function call inside your loop. Then the click will be processed.

DO WHILE .T.
* your loop code here

DOEVENTS()
IF [your exit condition here]
	EXIT
ENDIF
ENDDO