Starting a dialog minimized or hidden: how can I do it?

[Cesario Simões]

I want a hidding dialog because my application is dialog based and I`m using a tray icon...
I have tested your sugestion:
CAgendaDlg dlg;
here--> dlg.ModifyStyle (NULL, WS_VISIBLE, NULL);
int nResponse = dlg.DoModal();
but an erro occurs when the program execute it... I also have tested
dlg.ShowWindow(SW_HIDE); but the same error occurs...

Cesario Simões, Jr.