# 9.4. How to call Help in Dialogs

Calling help in dialogs is often done by adding a Help-button; then you add a slot that is called when the button gets pressed. Within the slot implementation, call

     kapp->invokeHTMLHelp( QString aFilename, QString aTopic );

where `aFilename` is the the filename to be called within your HTML documentation directory of the application; e.g index-3.html. `aTopic` then is the topic that is to be called. The hash prefix is automatically added; just enter the chapter you want to have on this page, actually this would be a subsection's name.