Re: 2 parm vs. 1parm GetDlgItem() trouble . . .

Thank you. I think I almost understand. Rough being a newbie :)

As used -- GetSafeHwnd(); results in Unhandled exception at 0x5c5278dc
(mfc90ud.dll) in tst04.exe:
for:
gMBs.CtlBtn.m_Btn->SetBitmap( gMBs.CtlBtn.m_Btmp );

gMBs.CtlBtn.m_Btn is set from:
reinterpret_cast<CButton *>(GetDlgItem(DlgH,gMBs.CtlBtn.Btn_ID));

within the mpc.cpp attached.

Clearly -- I am missing some large overall consideration rule or construct.

I am working on an application for a stroke patient (my mother). I am
learning C++ and VS and MFC -- I've been a 'C' since the dino days.
This app defines 6 (six) jumbo size touch buttons (for now mouse click
buttons), these jumbo buttons will have a graphic bitmap (this is working)
\via this test code:
BOOL C_tst_04_Dlg::OnInitDialog()
{ . . .
     static CBitmap m_bitmap;
     CButton *m_Btn_1;
     m_Btn_1 = reinterpret_cast<CButton *>(GetDlgItem(IDC_BUTTON1));
     m_bitmap.LoadBitmap(IDB_BITMAP_Btn_1);
     m_Btn_1->SetBitmap(m_bitmap);
. . . }

Because of false/error hits/taps the design is to require two discrete
taps with the
first tape inverting the bitmap on the button -- so it becomes tagged --
the
patient gets visual feedback of what they are trying to do.

So I created a button click / bitmap inverting class. -- there is a 7th
button that
will although "paging" to additional sets of six jumbo buttons. But the
logic will
be the same for each page -- takes two discrete touches/clicks with
unlimmited
time inbetween -- to trigger the buttons action. The default icon will
show -- when the first click is made this icon is inverted. Check the
attached
mpc.h and mpc.cpp (mpc is short for project MomPC).

BOOL C_tst_04_Dlg::OnInitDialog()
    { . . .
     HWND DlgH = GetSafeHwnd();
     gMBs.do_mpc_btn_init( DlgH ); // do the MPC button
initialization, bitmaps, counts, states, etc.
. . . }

The tasks being done but these jumbo buttons is quite varied -- it seemed
to be in good coding practices to isolate the button and screen of buttons
logic and processing, no? But what worked fine inside of
C_tst_04_Dlg::OnInitDialog() is not working within gMBs.do_mpc_btn_init( )?

Do I explain this well enough?