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From: matt@bacchus.esa.oz (Matt Atterbury)
Newsgroups: comp.windows.x
Subject: ProcessContext in X11R4 Xt library (bug?).
Message-ID: <MATT.91May9141022@henry.bacchus.esa.oz>
Date: 9 May 91 04:10:22 GMT
Sender: matt@bacchus.esa.oz.au
Distribution: comp
Organization: Expert Solutions Australia.
Lines: 47


    [Sorry if this has been fixed in a fix we don't have].

    All the manuals I have [O'Reilly and X] say that you should use
    XtAppInitialize rather than XtInitialize, so I did. But there is
    one thing that XtInitialize does that XtAppInitialize doesn't do,
    and that is to set up the [single, static] process context's
    defaultAppContext field [this is used extensivley in the Xt
    library]. The symptom was that a home-grown widget's translation
    table was being 'handled' OK but the action table for it was being
    ignored - result: 'Warning: Actions not found:' error messages.

    1st Question) is this a problem in XtAppInitialize or in the widget?

    The before code I had was:

        XtToolkitInitialize();
***     app_context = XtCreateApplicationContext();
        display = XtOpenDisplay(app_context, ...);
        toplevel = XtAppCreateShell(NULL, ...);

    The after code is:

        extern XtAppContext _XtDefaultAppContext();

        XtToolkitInitialize();
***     app_context = _XtDefaultAppContext();
        display = XtOpenDisplay(app_context, ...);
        toplevel = XtAppCreateShell(NULL, ...);

    _XtDefaultAppContext() will create an app context if there isn't a
    default already, and returns the default app context. The actions
    problem has gone away. Note that I cannot use XtInitialize since I
    am opening a number of displays.

    2nd Question) assuming the widget is OK, what is the ideologically
                  correct way of getting the default app context set
                  up properly [_XtDefaultAppContext is supposedly an
                  internal Xt routine - it may go away?]?

    Any information/responses welcome. cheers ...
--
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Matt Atterbury [matt@bacchus.esa.oz.au]   Expert Solutions Australia, Melbourne
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