以下代碼將演示一個150像數高的文件打開對話框，這個例子很簡單，我們要做的就是讓對話框更好看和有更多的用途。我們需要考慮的是怎么樣用MFC來更簡單的定義我們自己的對話框，這兒有許多地方是比較靈活的,所以我們可以把它搞得很好看。

    如果我們想改變對話框中控件的大小或者是它的顯示的樣子，當然包括對話框本身，僅僅使用GetDlgItem()函數是不夠的，因為控件是對話框子集中的一部分。控件的ID在頭文件dlgs.h中的定義如下：
    stc3,stc2    控件的標簽（文件名和文件類型）
    edt1,cmb1    編輯框控件和滾動條
    IDOK，IDCANCEL    OK和CANCEL按鈕
    lst1         顯示文件名的窗口

    當然如果你要用其它的控件的話，在頭文件中還有其它的定義，以下的CMyFileDialog類是從CFileDialog中的派生出來的，這當中我還添加了一個消息句柄WM_INITDIALOG。以下是原代碼：

////////////////////////////////////////////////////////////////
// This is where the real action is going on
// Remember #include <dlgs.h>
BOOL CMyFileDialog::OnInitDialog() // Override
{
    // This variable should be changed acording to your wishes
    // about the size of the finished dialog
    const UINT iExtraSize = 150;
    // Number of controls in the File Dialog
    const UINT nControls = 7;    

    // Get a pointer to the original dialog box.
    CWnd *wndDlg = GetParent();

    RECT Rect;
    wndDlg->GetWindowRect(&Rect);
    // Change the size
    wndDlg->SetWindowPos(NULL, 0, 0,
                        Rect.right - Rect.left,
                        Rect.bottom - Rect.top + iExtraSize,
                        SWP_NOMOVE);

    // Control ID's - defined in <dlgs.h>
    UINT Controls[nControls] = {stc3, stc2, // The two label controls
                                edt1, cmb1, // The eidt control and the drop-down box
                                IDOK, IDCANCEL,
                                lst1}; // The Explorer window

    // Go through each of the controls in the dialog box, and move them to a new position
    for (int i=0 ; i<nControls ; i++)
    {
        CWnd *wndCtrl = wndDlg->GetDlgItem(Controls[i]);
        wndCtrl->GetWindowRect(&Rect);
        wndDlg->ScreenToClient(&Rect); // Remember it is child controls

        // Move all the controls according to the new size of the dialog.
        if (Controls[i] != lst1)
            wndCtrl->SetWindowPos(NULL,
                            Rect.left, Rect.top + iExtraSize,
                            0, 0, SWP_NOSIZE);
        else // This is the explorer like window. It should be sized - not moved.
            wndCtrl->SetWindowPos(NULL, 0, 0,
                                Rect.right - Rect.left,
                                Rect.bottom - Rect.top + iExtraSize,
                                SWP_NOMOVE);
    }

    // Remember to call the baseclass.
    return CFileDialog::OnInitDialog();
}