The translation mechanism provides the application developers with a powerful syntax for specifying sequences of events and means to map them to actions. Actually, a level of redirection is introduced at this level. The event sequences are mapped into strings, which are mapped to executable procedures further in the program. This is intended to allow the mapping of events to actions to be specified through the resource database.

To specify translations programmatically the programmer can use one of these predicates: xtAugmentTranslations/2 or xtOverrideTranslations/2. Both of these predicates register a translation table with a particular widget. xtAugmentTranslations/2 merges the new translation table with the current one while xtOverrideTranslations/2 not only does that but also replaces existing translations with entries from the new translation table whenever there is a conflict.

The translation table is a structure that is opaque to the Prolog programmer. One can use the predicate xtParseTranslationTable/2 to parse the translations string and generate the translation table. The exact syntax of the translations string is explained in the X Toolkit documentation.

The predicate xtAppAddActions/2 is used to map the action names to executable procedures. The first argument is the application context and the second argument is a list of terms of type Action. In ProXT the translation procedures have three arguments -- the first argument is the widget where the event occurred, the second argument is the event that invoked the action and the third is a list of parameters specified in the action name.

Following is a reimplementation of the previous example using translations for event handling.

     create_button :-
                           [xmNwidth(100), xmNheight(100)],Button),
             xtAppAddActions(App, [action(foo,pressed)]),
             xtParseTranslationTable('<Btn1Down: foo("Hello Quintus")',
     pressed(Widget, Event, ParamList) :-
             write(Widget), nl,
             write(Event), nl,
             write(ParamList), nl.

Registering translations through the resource database is covered to the section dedicated on the resource database.