Modeless Dialog

Within a modal dialog I started a modeless dialog - how can I find out when the modeless dialog is going to be closed ?
(I tried a lot of things OnNotify(), OnChildNoitify(), OnParentNotify()..., but I could not find out)

[suresh_kolguri]

Use ASSERT statement and compare it with NULL in class of Modal less dialog.
ASSERT(if(IDD_MODALLESS != NULL))

Suresh kumar K