The source code can be found in SVN, module base/gpe-what.
Distributions known to ship gpe-what are:
gpe-what is distributed under the GPL.
GPE-what implements a modal help system for the GPE environment. It provides a "help" icon in the dock panel.
When this icon is clicked, the system enters "help mode"; normal UI is suspended, and the next mouse click selects the widget for which help is wanted. The help text, if available, is displayed in a small pop-up bubble. This mechanism much much more useful for touchscreen use compared to the "mouse-over" tooltips known from a desktop PC.