Via the suggestion box, Matthew Douglass-Riley wonders about the history and fate of the What's This? button. (The same question was repeated by an anonymous coward.)
The What's This? button (more formally known as the contextual help caption button) is turned on by the
WS_ extended style and takes the form of a question mark. When the user clicks the button, the cursor changes to an arrow with a question mark, and when the user clicks on a child window, a
WM_ message is delivered to that window.
As originally written, the intended response is for the window to call the
WinHelp function with the
HELP_ command and information describing the location of the desired help text. The
WinHelp.exe program displays the help text in a pop-up window.
As a clue to how old this technology is, you may observe that the pop-up window causes the original window to become disabled, and it comes with a rather sad looking shadow effect. This was long before the introduction of the
CS_ window style or even layered windows. To get a drop shadow effect, you had to draw it yourself. And this was also the days of 4-bit color, so the drop shadow effect is actually a dither.
Anyway, it wasn't long for What's This? to fall out of favor and become replaced with HTML Help, which in turn has taken a back seat to Windows Vista Help. It seems that help technologies change rather often, and I'm not sure why. Maybe it's because the user assistance folks are willing to experiment with a lot of different ideas, unashamed of abandoning their previous efforts when they fail to pan out. Maybe because designing a good help system is hard. Maybe because users simply don't bother checking the help, so it doesn't matter how good your help system is since nobody uses it anyway.
I find it interesting that the Help Guidelines asks the question, "Are you using Help to fix a bad UI?" There's even an entire section titled Designing UI so that Help is unnecessary. I find the guidelines interesting because they capture lessons learned from earlier versions of Windows which violated those guidelines.
Matthew calls out one particular dialog in Windows XP that has a non-functional contextual help caption button. Sorry about that. It's a leftover from the days when contextual help was still the recommended way of providing user assistance. The contextual help was removed, but the button wasn't cleaned up. You'll be happy to learn that the UI glitch has been fixed in Windows Vista.