Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!uwvax!rennet.cs.wisc.edu!stuart
From: stuart@rennet.cs.wisc.edu (Stuart Friedberg)
Newsgroups: comp.windows.x
Subject: Dynamically Replacing Widget Translations
Message-ID: <6892@spool.cs.wisc.edu>
Date: 18 Dec 88 02:46:52 GMT
Sender: news@spool.cs.wisc.edu
Reply-To: stuart@rennet.cs.wisc.edu (Stuart Friedberg)
Distribution: na
Organization: U of Wisconsin CS Dept
Lines: 47

I started to make a Toggle widget as a subclass of Command using
state-sensitive translation tables, rather than state-sensitive
actions.  I intended to compile two translation tables during
ClassInitialize, record them in the subclass's ToggleClassPart, and
install them in the widget instance's CorePart on the fly.

Then I discovered I didn't know how to completely replace a translation
table.  A CorePart TMRec is more than an XtTranslations, which is what
the translation compiler returns.

Question 1a: Am I attempting something against the spirit of X or the
             Athena Toolkit?
Question 1b: If so, what is an approach in the approved spirit to provide
             state-sensitive behavior?

Poking around the R3 Xt/TMstate.c, it seems that the common code
to XtOverrideTranslations and XtAugmentTranslations does what I
want, namely

    if (XtIsRealized(widget)) {
        XtUninstallTranslations(widget);
        ((WindowObj)widget)->win_obj.tm.translations = newTable;
        _XtBindActions(widget, &((WindowObj)widget)->win_obj.tm, 0);
        _XtInstallTranslations(widget, newTable);
    }
    else ((WindowObj)widget)->win_obj.tm.translations = newTable;

Question 2a: Is there more to it than that?
Question 2b: If not, wouldn't this be a good candidate for encapsulation
             as a new public function: _XtReplaceTranslations?

Looking back into the R2 sources, which are what I am running now,
XtUninstallTranslations doesn't exist, and _XtInstallTranslations is
never used.

Question 3a: Can Core be substituted safely for WindowObj?
Question 3b: Can the R3 code for XtUninstallTranslations be used in R2?
Question 3c: With those substitutions, will the R3 solution work in R2?
Question 3d: If not, is it all practical to attempt tm table replacement in R2?

Finally and somewhat peripherally,

Question 4a: Is the Core => Object + RectObj + WindowObj split complete?
Question 4b: Where can I find the documentation about it (purpose,
             proposed new subclasses of Object and RectObj, etc)?

Stu Friedberg  stuart@cs.wisc.edu