I have a working mdi application that for user friendliness should be an sdi.
Problem #1 is that the mdi application has buttons on the toolbar that invoke
various windows that float on top of the application.  When I convert the
application to sdi, the windows don't display properly.  The person I talked to at
MSDN technical support couldn't figure out how to do it and said I should either
try resizeable dialog windows or make the mdi act like an sdi.  Trying the second
route leads to problem #2, the reason I wanted to go to sdi in the first place.
How do I make the document appear maximized and remove the min, max, and close
buttons for the document?

Alternatively, in a sdi, how do I create non-modal windows that can float on top
of the application?

Refer to the following steps:

1) Create a CDialog* variable in CView class named m_testdlg;

2) In CView construction method:
  m_testdlg = new CDialog;

3) In CView destruction method:
  delete m_testdlg;

4) In any other message command handlers that you want to show a dialog:
  m_testdlg.Create( IDD_***, this);
  m_testdlg.ShowWindow(SH_SHOW);

I think that if the dialog is going to be allocated in the constructor and
deleted in the destructor, then it is easier to combine steps 1 to 3 and
just put something such as the following in the CView class:

    CDialog m_testdlg;

I have done things like that and it works for me.

Also for modeless dialogs, "you must override" OnOk and OnCancel as
specified in the documentation for CDialog::OnCancel and CDialog::OnOk
respectively.

I have some notes at:

http://www.cpp.atfreeweb.com/ModelessDialogs.html

If anyone has any fixes, suggestions or any other comments about my notes,
let me know.