How TApplication Processes VCL Help

TApplication in the VCL provides four methods that are accessible from application code:

Help methods in TApplication

Method	Description
HelpCommand	Takes a Windows Help style HELP_COMMAND and passes it off to WinHelp. Help requests forwarded through this mechanism are passed only to implementations of IspecialWinHelpViewer.
HelpContext	Invokes the Help System with a request for context-based Help.
HelpKeyword	Invokes the HelpSystem with a request for keyword-based Help.
HelpJump	Requests the display of a particular topic.

All four functions take the data passed to them and forward it through a data member of TApplication, which represents the Help system. That data member is directly accessible through the property HelpSystem.