Advanced MFC Programming

Chapter 16. Context Sensitive Help
The edit box and radio button still use the default style, whose help window contains standard menu
and buttons. The help windows of push button and combo box controls are implemented by pop up
window, which is a smaller window with a yellowish background, and does not contain other controls
(Figure 16-10). By passing different parameters to function CWinApp::WinHelp(…), we can activate “Help
Topic” dialog box. Also, we can adjust its position and size of the help window before it is displayed,.
Display help in a
pop up window
Figure 16-10. Pop up Help Window
Summary
1) In order to implement context sensitive help for a command, we need to add a footnote to the
“AfxCore.rtf” file, then link the command ID to the tag of the footnote.
2) Usually the help ID is generated by prefixing character(s) to the resource ID of the command, and the
value of the help ID is generated by adding a fixed number to the value of the resource ID.
3) The resource ID can be linked to a footnote tag by specifying an alias name in “.hpj” file.
4) A help page can be referenced either from other help pages or from the application.
5) To support context sensitive help in the dialog box, we need to call function CWnd::
SetWindowContextHelpId(…) for every common control that will support context sensitive help, and
override function CWnd::OnHelpInfo(…) to activate customized help window.
6) By default, function CWnd::OnHelpInfo(…) does not support context sensitive help for common
controls. In this case, we can call CWinApp::WinHelp(…) to customize the default help implementation.
7) When calling function CWinApp::WinHelp(…), we can use various parameters to activate help windows
in different styles. For example, using parameter HELP_CONTEXTPOPUP will invoke a pop up help
window.
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