🚀 go-pugleaf

i would appreciate someone's help with the following windows
problem (i wish there was better windows documentation).
 
i am trying to create my own windows subclass. i created a
dialog box using the sdk dialog editor. the diaolg actually
contains 12 edit controls. i want some of those controls to
accept only numeric characters. i need to trap te WM_CHAR
messages and to accept only those with numeric character
values. i created NumericProc to handle this:
 
FARPROC lpfnNumericProc;
FARPROC lpfnOldEdit;
 
long FAR PASCAL NumericProc(HWND hwnd, WORD message, WORD wParam, LONG lParam)
{
extern FARPROC lpfnOldEdit;
  switch(message)
  {
    case WM_CHAR:
    if (!isdigit(wParam))
      MessageBeep(0);
    break;
  }
  return CallWindowProc(lpfnOldEdit,hwnd,message,wParam,lParam);
}
 
 
i get the instance of the proc in WinMain as follows:
 
  lpfnNumericProc = MakeProcInstance((FARPROC)NumericProc, hInstance);
 
 
i call "DialogBox". The following is the dialog box code.
 
BOOL FAR PASCAL DlgProc(HWND hDlg, WORD message, WORD wParam, LONG lParam)
{
static int iCurrentFieldType;
extern FARPROC lpfnNumericProc;
switch(message)
  {
    case WM_INITDIALOG:
    return TRUE;
 
    case WM_COMMAND:
    switch(wParam)
    {
      case IDOK:
      EndDialog(hDlg,TRUE);
      return TRUE;
 
      case IDCANCEL:
      EndDialog(hDlg,FALSE);
      return TRUE;
 
      default:
      if (HIWORD(lParam) == EN_SETFOCUS)
      {
// get field type
        iCurrentFieldType = FieldType(GoldCosts, NUM_GOLD_COSTS, iCurrentControl);
        switch(iCurrentFieldType)
        {
          case NUMERIC:
// use numeric control
          lpfnOldEdit = (FARPROC)GetWindowLong(hDlg,GWL_WNDPROC);
          SetWindowLong(hDlg, GWL_WNDPROC,(LONG) lpfnNumericProc);
          break;
          default:
          break;
        }
      } 
      if (HIWORD(lParam) == EN_KILLFOCUS)
      {
// reset to original edit control
         SetWindowLong(hDlg, GWL_WNDPROC,(LONG) lpfnOldEdit);
      } 
      return FALSE;
    }
  }
  return FALSE;
}
 
The above code doesn't work. i think it is because i am not
passing the proper handle of the edit control. ( i am
passing the address of the current dialog box). if i
understand things correctly, i need to pass the address of
the edit control. is that right? if so, how do i obtain the
handle of the original (or current) edit control handle? if
not, what am i doing wrong?
 
thanks for your help
moshe raab
raab@novavax