[Excerpt from resfmt.zip...]

4.3  Dialog Box Resources

A dialog box is contained in a single resource and has a
header and a portion repeated for each control in the dialog
box.  The header is as follows:

    [Resource header (type = 5)]
    
struct DialogBoxHeader {
  DWORD  lStyle;
  DWORD  lExtendedStyle;     // new for NT
  WORD   NumberOfItems;
  WORD   x;
  WORD   y;
  WORD   cx;
  WORD   cy;
  [Name or Ordinal] MenuName;
  [Name or Ordinal] ClassName;
  WCHAR  szCaption[];
  WORD   wPointSize;         // Only here if FONT set for dialog
  WCHAR  szFontName[];       // This too
  };
  
The item DWORD lStyle is a standard window style composed of
flags found in WINDOWS.H.    The default style for a dialog
box is:

    WS_POPUP | WS_BORDER | WS_SYSMENU
    
The lExtendedStyle DWORD is used to specify the extended
window style flags.  If an extended style is specified on
the DIALOG statement, or with the other optional modifier
statements, this DWORD is set to that value.

The items marked `Name or Ordinal' are the same format used
throughout the resource file (most notably in each resource
header) to store a name or an ordinal ID.  As before, if the
first word is an 0xffff, the next two bytes contain an
ordinal ID.  Otherwise, the first 1 or more WORDS contain a
double-null-terminated string.  An empty string is
represented by a single WORD zero in the first location.

The WORD wPointSize and WCHAR szFontName entries are present
if the FONT statement was included for the dialog box.  This
can be detected by checking the entry lStyle.  if lStyle &
DS_SETFONT (DS_SETFONT = 0x40), then these entries will be
present.

The data for each control starts on a DWORD boundary (which
may require some padding from the previous control), and its
format is as follows:

struct ControlData {
  DWORD  lStyle;
  DWORD  lExtendedStyle;
  WORD   x;
  WORD   y;
  WORD   cx;
  WORD   cy;
  WORD   wId;
  [Name or Ordinal] ClassId;
  [Name or Ordinal] Text;
  WORD   nExtraStuff;
  };
    
As before, the item DWORD lStyle is a standard window style
composed of the flags found in WINDOWS.H.  The type of
control is determined by the class.  The class is either
given by a zero-terminated string, or in the case of many
common Windows classes, is given a one word code to save
space and speed processing - in this case, the ordinal
number will be a WORD in length, but only the lower byte
will be used.  Because UNICODE allows 0x8000 as a legal
character, the ordinal classes are prefaced with a of
0xFFFF, similar to the ordinal Type and Name fields.  The
one byte classes are listed here:

    #define    BUTTON              0x80
    #define    EDIT                0x81
    #define    STATIC              0x82
    #define    LISTBOX             0x83
    #define    SCROLLBAR           0x84
    #define    COMBOBOX            0x85
    
The lExtendedStyle DWORD is used to specify the extended
style flags to be used for this control.  The extended style
flags are placed at the end of the CONTROL (or other control
statements) statement following the coordinates

The extra information at the end of the control data
structure is currently not used, but is intended for extra
information that may be needed for menu items in the future.
Usually it is zero length.

The various statements used in a dialog script are all
mapped to these classes along with certain modifying styles.
The values for these styles can be found in WINDOWS.H.  All
dialog controls have the default styles of WS_CHILD and
WS_VISIBLE.  A list of the default styles used to make the
script statements follows:

Statement       Default Class  Default Styles

    CONTROL         None           WS_CHILD | WS_VISIBLE
    LTEXT           STATIC         ES_LEFT
    RTEXT           STATIC         ES_RIGHT
    CTEXT           STATIC         ES_CENTER
    LISTBOX         LISTBOX        WS_BORDER | LBS_NOTIFY
    CHECKBOX        BUTTON         BS_CHECKBOX | WS_TABSTOP
    PUSHBUTTON      BUTTON         BS_PUSHBUTTON | WS_TABSTOP
    GROUPBOX        BUTTON         BS_GROUPBOX
    DEFPUSHBUTTON   BUTTON         BS_DEFPUSHBUTTON | WS_TABSTOP
    RADIOBUTTON     BUTTON         BS_RADIOBUTTON
    AUTOCHECKBOX    BUTTON         BS_AUTOCHECKBOX
    AUTO3STATE      BUTTON         BS_AUTO3STATE
    AUTORADIOBUTTON BUTTON         BS_AUTORADIOBUTTON
    PUSHBOX         BUTTON         BS_PUSHBOX
    STATE3          BUTTON         BS_3STATE
    EDITTEXT        EDIT           ES_LEFT | WS_BORDER | WS_TABSTOP
    COMBOBOX        COMBOBOX       None
    ICON            STATIC         SS_ICON
    SCROLLBAR       SCROLLBAR      None
    
The control text is stored in the `Name or Ordinal' format
described in detail above.