Integrating Microsoft HTML Help search into .NET applications

October 20, 2005

While spending countless hours writing a comprehensive help file is infinitely rewarding for application testing, consistency and design; it counts for a lot more if users can perform quick help searches from inside the application. That little help search box in the top right hand corner of Office 2003 applications is worth its weight in gold.

The HelpProvider in .NET doesn’t provide a method to run help searches from your application. After digging around we found .NET wrapper code to use the unmanaged HTML Help API. While this unmanaged API has an appropriate method, it turns out that HTML Help 1.4 has a bug which ignores the search information struct anyway. So, it will never work. I guess that’s why they didn’t provide a method to do it from inside .NET.

Of course, rather than thinking about fancy APIs etc we can always fall back on the simplest thing that will possibly work:

// Open the help window to the search
paneHelp.ShowHelp(this, Application.StartupPath + Path.DirectorySeparatorChar + "SauceReader.chm", HelpNavigator.Find, "");
// run the search, by sending key strokes to now active help
windowSystem.Windows.Forms.SendKeys.SendWait("{HOME}^+{END}{BACKSPACE}search query{ENTER}");
// select the first result

Note: Originally posted to my Synop blog on April 2, 2004.