Highlights

There are a number of changes from the previous version of ProXT that was released with Quintus Prolog 3.1. These changes are summarized as follows:

• Predicates and attributes that used to take a CharPtr type now take a String type, which is represented as a Prolog atom. This means that the predicates proxtCharPtrToString/2 and proxtStringToCharPtr/2 are obsolete.
• The predicate proxtGetDefaultCharset/1 is obsolete. In Motif2.1, most functions that used to take a Charset parameter now take a FontListTag parameter and the atom xmDEFAULT_FONTLIST_TAG can be used as a FonListTag.
• All predicates that correspond to Boolean functions in Motif now succeed or fail according to whether the Motif function returns true or false. This means that some predicates that used to include a Results parameter have been replaced by predicates with that argument removed.
• The Calldata argument returned by widget callbacks is now a handle, rather than a list of field, that can be inspected (and modified) by three new proxt predicates: the callback reason can be extracted by the predicate proxtGetCallbackReason/2; a list of all fields is returned by proxtGetCallbackFields/2 (the contents of this list varies depending on the type of callback); and finally a list of fields to be modified can be specified in proxtSetCallbackFields/2.
• ProXT will now backtrack through callback predicates if they return nondeterminately.
• The client data argument in the Action datatype has been dropped and similarly the client data argument to action callbacks has been dropped. Instead parameters specified in the translation table are now passed into the action callback as a list of items of type String in the third argument. The second argument to the action callback is now the Event.
• Attributes that used to be of type CallbackList are now of type CallbackTerm, that is, they take a single callback as value, not a list of callbacks.

  The format of datatype XRectangle has changed. This is now a term of the form rectangle(X,Y,Width,Height).

• The format of datatype XmClipboardPendingList has changed. This is now a list of terms of the form clipboardpending(DataId,PrivateId).
• The return value of xtPending/1 has changed, returning an XEventMask type rather than a mask/1 structure.
• The predicate proxtGetDefaultGC/2 is obsolete. The predicate xCreateGC/4 should be used to define a GC graphics context.
• The predicate proxtFree/1 has been renamed xtFree/1.
• The values returned as datatype ClipboardStatus have been renamed from clipboard* to xmClipboard* in line with the change made in Motif2.1.
• Some values included in the datatype XmDialogType have changed.
• The predicate xtOpenDisplay now has an additional argument specifying the AppName.

One of the main changes to ProXT 3.5 concerns the ability to extend ProXT with new widget classes and resources. The file demo(proxrt.pl) demonstrates how a graph widget can be incorporated into ProXT.