popup size = cview size

Hi,

is it possible to change the size of a modal popup dialog to the size
of the mainframe (cformview) ? Using a SDI application, I have a
button on my derrived class from the CFormView class. By clicking on
this button another dialog (popup) should be called

CTouchCalibrationDialog dlg;
dlg.DoModal();

Within this dialog I want to calibrate my touch display. I know one
solution would be to use ShowWindow(SHOW_MAXIMIZED) in the
OnInitDialog() method of this popup dialog. Is there another solution?
Working on the specific hardware / lcd monitor with the resolution
800x480 ShowWindow(Maximized) will be ok, but I often have to programm
some new things using a normal windows computer with a different
monitor and a much higher resolution.

To get always the correct width / height resolution 800x480 I`m using
the OnCreate() method of my cmainframe class. I`m not sure if these
commands are correct, but I get the desired resolution of 800x480.

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CFrameWnd::OnCreate(lpCreateStruct) == -1)
        return -1;

    int nXpx = 533, nYpx =295;
    CRect rect(0, 0, nXpx, nYpx);
    MapDialogRect(m_hWnd, &rect);
    int nXdbu = rect.right;
    int nYdbu = rect.bottom;

                //m_height = 480 | m_width = 800; (member of my
cmainframe class)

    CRect m_rc( 0, 0, ((m_width * nXpx) / nXdbu), ((m_heigth * nYpx) /
nYdbu));
    MoveWindow(m_rc);
    return 0;
}

Are these values specific to my video card (nXpx, nYpx )? So that I`ve
to calculate these items to get always the desired resolution?

Moreover which steps do I have to include in the OnCreate() method of
my popup dialog to get the same resolution and size of this dialog as
for the cformview?

best regards
Hans