The What's This? command supports a user obtaining contextual information about any object on the screen, including controls in property sheets and dialog boxes. This form of contextual user assistance is referred to as context-sensitive Help. As shown in Figure 12.1, you can support user access to this command by including:
Figure 12.1 Different methods of accessing What's This?
Design your application so that when the user chooses the What's This? command from the Help drop-down menu or clicks a What's This? button, the system is set to a temporary mode. Change the pointer's shape to reflect this mode change, as shown in Figure 12.2. The SHIFT+F1 combination is the shortcut key for this mode.
Figure 12.2 A context-sensitive Help pointer
Display the context-sensitive Help pointer only over the window that provides context-sensitive Help; that is, only over the active window from which the What's This? command was chosen.
In this mode, when the user clicks an object with mouse button 1 (for pens, tapping), display a context-sensitive Help pop-up window for that object. The context-sensitive Help window provides a brief explanation about the object and how to use it, as shown in Figure 12.3. Once the context-sensitive Help window is displayed, return the pointer and pointer operation to its usual state.
Figure 12.3 A pop-up window for context-sensitive Help
If the user presses a shortcut key that applies to a window that is in contextual Help mode, you can display a contextual Help pop-up window for the command associated with that shortcut key.
However, there are some exceptions to this interaction. First, if the user chooses a menu title, either in the menu bar or a cascading menu, maintain the mode until the user chooses a menu item and then display the context-sensitive Help window. Second, if the user clicks the item with mouse button 2 and the object supports a pop-up menu, maintain the mode until the user chooses a menu item or cancels the menu. If the object does not support a pop-up menu, the interaction should be the same as clicking it with mouse button 1. Finally, if the chosen object or location does not support context-sensitive Help or is otherwise an inappropriate target for context-sensitive Help, cancel the context-sensitive Help mode.
If the user chooses the What's This? command a second time, clicks outside the window, or presses the ESC key, cancel the context-sensitive Help mode. Restore the pointer to its usual image and operation in that context.
When the user chooses the What's This? command from a pop-up menu (as shown in Figure 12.4), the interaction is slightly different. Because the user has identified the object by clicking mouse button 2, there is no need for entering the context-sensitive Help mode. Instead, immediately display the context-sensitive Help pop-up window for that object.
Figure 12.4 A pop-up menu for a control
The F1 key is the shortcut key for this form of interaction; that is, pressing F1 displays a context-sensitive Help window for the object that has the input focus.