dialog template

  A dialog template is a Windows data structure called DLGTEMPLATE or
  TDlgTemplate. It consists of
   -  a dialog template header (required)
   -  font information for the dialog (optional)
   -  template information for each of the items in the dialog box
     (optional)

  A pointer to the structure is used by:
    CreateDialogIndirect
    CreateDialogIndirectParam
    DialogBoxIndirect
    DialogBoxIndirectParam

  Dialog templates begin with a dialog template header. The header consists
  of:
     dtStyle      The style of the dialog box (long integer). This value can
                  be one of, or any combination of, the ds_ Dialog style
                  constants.
     dtItemCount  The number of items in the dialog box (byte).
     dtX, dtY     The coordinates of the upper-left corner of the dialog
                  box, relative to the origin of the parent window's client
                  area. (If the dialog's style includes ds_AbsAlign, the
                  coordinates are relative to the origin of the screen.)
     dtCX, dtCY   The width and height of the dialog box.

  Here is an example of a dialog template header:
    type
      DialogTemplateHeader = record
        dtStyle: Longint;
        dtItemCount: Byte;
        dtX, dtY: Integer;
        dtCX, dtCY: Integer;
      end;

  Three null-terminated strings follow the coordinates and size of the
  dialog box:
     dtMenuName      the name of the dialog box's menu
     dtClassName     the name of the dialog box's Windows class
     dtCaptionText   the dialog box's caption.

  If dtStyle contains ds_SetFont, dtCaptionText must be followed by two
  items describing the font:
   -  the point size of the typeface (short integer)
   -  the name of the typeface (null-terminated string)

  Dialog item templates follow the font information. There is one dialog
  item template for each control in the dialog box. The number of items is
  determined by dtItemCount .

  Each dialog item template consists of:
     dtilX, dtilY,    the position and size of the control,
     dtilCX, dtilCY   relative to the origin of the dialog (integers).
     dtilID           an integer which gives the dialog item ID of the
                      control.
     dtilStyle        the style of the dialog-box item (long integer).
     one of: BUTTON,
     EDIT, STATIC,
     LISTBOX, SCROLLBAR,
     COMBOBOX           name of the control's Windows class
                        (null-terminated string).
     dtilText           the text for the item (null-terminated string).
     dtilInfo           value indicating the number of bytes of additional
                        information  (byte). 0 indicates that there is no
                        additional information.
     dtilData           information that is passed to CreateWindow  in the
                        CreateParams field of a TCreateStruct. Used only if
                        dtilInfo is non-zero.

  GetDialogBaseUnits