You mean you defined a class form in code, in a .prg?
If so, then you can set the property based on a parameter or some conditions, like:

*-- yourProg.prg
parameter tnShowWin
private nShowWin

nShowWin = iif(type('tnShowWin')='N', tnShowWin, 0)

loForm=createobject('myForm')

define class myForm as form
...
	showwindow = nShowWin
...
enddefine

>I wrote code to define a form.If design this form with Form Designer set ShowWindow property to 1(in top-level form).How make this in code ? (because this property is available at design time,read only at run time)
>
>Thanks in advance,