顶层表单可以做表单集吗？

简单的就这样：
of = CREATEOBJECT("myPreviewForm")
of.show
REPORT FORM 报表.frx PREVIEW IN WINDOW (of.Name)
IF VARTYPE(of) == "O"
    of.Release
ENDIF
RETURN

DEFINE CLASS myPreviewForm as Form
    Desktop = .T.
    ShowWindow = 2
    WindowState = 2
ENDDEFINE