provides support for displaying
balloons. After loading this library, a
event causes the system to look for a graphical
<-help_message method. If
tag yields a string, the library shows a little window with the message.
Moving the pointer out of the area of the graphical or pressing a button
causes the feedback window to disappear.
This tenchnique is commonly used in modern interfaces to provide feedback on the functions behind icons. See also section 11.3.2.
In addition to registering the global event-handler, the library
->help_message to the classes visual, graphical
tag(balloon) or extensive help message (
summary) for the receiving object. At the moment
summaryis not used.
->help_message. User-defined classes may consider redefining this method to generate the help-message on-the-fly.
Here is a typical usage for this library.
:- use_module(library(help_message)). resource(print, image, image('16x16/print.xpm')). ... send(X, append, new(B, button(print))), send(B, label, image(resource(print))), send(B, help_message, tag, 'Print document'),