Context-sensitive help the user can display for a visible feature in an application. An application may provide access to Popup Help in response to one or more of these user actions:
1. The user presses the F1 key to view Popup Help for the currently highlighted window control.
2. The user right-clicks the mouse on a window control and selects the "What's This?" context menu item.
3. The user clicks a "question mark" button 
on the window to turn the mouse pointer into an "arrow+question mark:"
The user then moves the mouse pointer over a
window control and clicks to display its Popup Help.
TMFMHelp is a Delphi VCL that enables application developers to add Popup Help to their applications easily. See: Help File.