add an icon in the upper right corner of the window title bar

[Kevin]

in dialog editor  click dialog titlebar and  click style button
 then select WS_EX_CONTEXTHELP click ok on styles window then click save on dialog editor window
then add the following  code below 
    case WM_COMMAND goto messages2

Code:

Copy      Help

,case WM_SYSCOMMAND
,sel wParam&0xfff0
,,case SC_CONTEXTHELP
,,mes "help"
,,ret 1

full code using your posted example

Code:

Copy      Help

str md=
;BEGIN MENU
;>&File
;,&Open :501 0x0 0x0 Co
;,&Save :502 0x0 0x0 Cs
;,>Submenu
;,,Item1 :551
;,,Item2 :552
;,,<
;,-
;,E&xit :2
;,<
;>&Edit
;,Cu&t :601
;,&Copy :602
;,&Paste :603
;,<
;>&Help
;,&About :901
;,<
;END MENU

;;menu bar example:
;;popup menu example:
;int i=ShowMenu(md); out i

str dd=
;BEGIN DIALOG
;0 "" 0x90C80AC8 0x400 0 0 224 136 "Dialog" "4"
;1 Button 0x54030001 0x4 116 116 48 14 "OK"
;2 Button 0x54030000 0x4 168 116 48 14 "Cancel"
;END DIALOG
;DIALOG EDITOR: "" 0x2040801 "*" "" "" ""

;if(!ShowDialog(dd &sub.DlgProc 0)) ret
if(!ShowDialog(dd &sub.DlgProc 0 0 0 0 0 0 0 0 0 md)) ret


#sub DlgProc
function# hDlg message wParam lParam

sel message
,case WM_INITDIALOG
,case WM_DESTROY
,case WM_COMMAND goto messages2
,case WM_SYSCOMMAND
,sel wParam&0xfff0
,,case SC_CONTEXTHELP
,,mes "help"
,,ret 1    
ret
;messages2
sel wParam
,case IDOK
,case IDCANCEL
ret 1

see link below to topic
dlg_context_help