Internet Info 1994 March/Internet Info CD-ROM (Walnut Creek) (March 1994).iso/answers/comp/motif-faq/part2

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From: [e-mail] (Brian Dealy)
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Subject: Motif FAQ (Part 2 of 5)
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Archive-name: motif-faq/part2
Last-modified: APR 04, 1994
Version: 3.6







-----------------------------------------------------------------------------
Subject: 31)  TOPIC: MOTIF GENERATORS

-----------------------------------------------------------------------------
Subject: 32)  What prototyping tools are there to generate Motif code?

[Last modified: June 93]

Answer: [An FAQ is for "personal opinions" on these tools.  I don't think it
is appropriate to give such opinions through this particular posting, so I
haven't included any. I will include vendor-provided descriptions provided
they are consise and informative]

`Prototyping tools' come in two forms: those that can be used to design the
interface only (GUI builder), and those that go beyond this to give support
for application code (User Interface Management Systems).  There are a number
of commercial and non-commercial tools of both kinds that will support the
Motif interface.  They include:

GUI builders:

Builder Xcessory
iXBUILD (formerly X Build)
ExoCODE/xm
MOTIFATION
X-Designer
Druid


UIMS:

WINTERP
ALEX
TAE Plus
Widget Creation Library
UIMX
Serpent
TeleUse
XFaceMaker2
MetaCard
ezX User Interface Management System


Some contact addresses are:



TAE Plus: Don Link, Century Computing, Inc. [phone] [e-mail]

TAE Plus is a mature, portable software development environment that supports
rapid building, tailoring, and management of Motif-based graphical user
interfaces.  The code generator can produce C, C++ and Ada code and allows for
merging regenerated code with previously modified parts of the interface.  You
an also generate a UIL/Mrm representation of your interface.  Scripting
capabilities are provided which facilitate automatic testing, on-line demos,
and tutorials.  A record and playback feature lets you build scripts simply by
interacting with your GUI.  A library of Dynamic Data Objects allows the user
to create truly graphical objects whose dynamic portions can reflect data as
well as be directly manipulated by the end-user. TAE Plus is available on
virtually all the standard X platforms and comes with a wide array of support
vehicles. (i.e., support office, newsletter, user's conference, etc.)

WINTERP: You may obtain the current source, documentation, and examples via
anonymous ftp from host export.lcs.mit.edu: in directory contrib/winterp you
will find the compress(1)'d tar(1) file winterp.tar.Z. If you do not have
Internet access you may request the source code to be mailed to you by sending
a message to [e-mail] or hplabs!hplnpm!winterp-
source.

Serpent: The S/W is free (anonymous ftp) from ftp.sei.cmu.edu.  For more info
contact erik/robert at [e-mail].  This is no longer supported,
and is apparently replaced by a commercial product called Alpha.  TeleUSE:
Built around X Windows and OSF/Motif, TeleUSE's comprehensive toolset gives
you maximum control over every phase of graphical user interface development,
including static screen layout and design, automatic implementation of
callbacks, building the executable, and the interactive test, debug, and
maintenance cycles.

For more information, please contact:

In North America and countries not specified below:

Alsys (formerly TeleSoft)
10251 Vista Sorrento Parkway Suite 300
San Diego, CA 92121 USA

[phone] X244
[phone] (fax)
[e-mail]

In France: [phone]
In the UK: [phone]
In Scandinavia: [phone]
In the Benelux: [phone]
In Germany: [phone]
In Italy: [phone]
In Japan: [phone]
In South Korea: [phone]



Builder Xcessory from ICS.  More details are available by sending a request to
[e-mail].  Address: ICS Inc., 201 Broadway, Cambridge MA 02139, Tel. (617)
621-0060, Fax. [phone]

X-Designer: From Imperial Software Technology in the UK.  Email address is
[e-mail].  ([phone]

Recently, V.I. Corporation have become the distributor for the X-Designer
product in the United States.  In addition, IST and V.I. Corporation have
developed a product called DVX-Designer that merges X-Designer with their GUI
product called DataViews.  Other merged products are in the works.  For more
information, people can contact:

        V.I. Corporation
        47 Pleasant Street
        Northampton, MA  01060
        Phone: [phone]
        Fax: [phone]
        Email: [e-mail]

ExoCODE/xm: From Expert Object Corp., 7250 Cicero Avenue, Lincolnwood, IL
60646 [phone].

X Build: iXOS Software GmbH, Bretonischer Ring 12,
        8011 Grasbrunn/Munich,
        Germany,
        email [e-mail] or [e-mail],
        phone ++49-89-46005 0

or in the US

        UniPress Software,
        2025 Lincoln Hwy.,
        Edison, NJ 08817,
        phone [phone]

ExoCode: From EXOC (Chicago, IL)

UIMX: Visual Edge Software Limited, 3870 Cote Vertu, St Laurent, Quebec, H4R
1V4, Phone: [phone], Fax:   [phone], or: Visual Edge Software
Ltd., 101 First Street, Suite 443, Los Altos, CA 94022, Phone: [phone],
Fax:   [phone]

The Widget Creation Library: The distribution is available in several ways.
The preferred approach it for you to get the compressed tar file using
anonymous ftp from:

    export.lcs.mit.edu    (18.30.0.238) /contrib/Wcl.1.06.tar.Z


XFaceMaker2: NSL -  Non Standard Logics S.A., 57-59, rue Lhomond, 75005  Paris
- France, Phone: [phone], Fax:   [phone] email:
[e-mail] or [e-mail] for information.

Their North American office: Non Standard Logics, Inc., 4141 State Street,
Suite B-11, Santa Barbara CA 93110, Tel: [phone], Fax: [phone]


MOTIFATION: PEM GmbH, Vaihinger Strasse 49, 7000 Stuttgart 80, Germany, Tel:
[phone], Fax: [phone] Email: [e-mail].
Available for (Motif 1.2/1.1) on SunOS, Solaris 2.1, HP, Interactive, ODT 3.0,
Silicon Graphics, PCS, ...


ALEX: For more information contact Michael Karliner on ([phone] or
E-mail to [e-mail].  ALEX Technologies, Waterman's Yard, 32a The
Mall, Ealing, London W5, UK.

MetaCard: MetaCard 1.0 is supported on five popular UNIX/X11 platforms: SPARC,
Sun3, DECstation, HP-9000/300, and SCO ODT.  An HP-9000/700 port is underway
and should be available by the end of July.  [They] plan to support IBM
RS/6000, SGI Iris, and DG AViiON sometime fall '92.  For more information, or
to receive a free save-disabled but licensable copy of MetaCard, email to
[e-mail] or call 303- 447-3936.  If you have anonymous FTP access to
the Internet, you can download the current engines, documentation, and an
unlicensed Home stack from ftp.metacard.com (128.138.213.21), directory
MetaCard.  Commercial users can get MetaCard from world.std.com
(192.74.137.5), directory pub/Metacard.  If you don't have an anonymous ftp
access, you can also download MetaCard from The World using kermit or xmodem
from the ~ftp/pub/MetaCard directory.  Sign up by calling 617-739-0202 (voice)
or via modem by dialing 617-739-9753 (7 bits even parity) and logging in as
new.

MetaCard 1.2 Beta 5 is now available for anonymous FTP from ftp.metacard.com
(directory MetaCard/1.2B5), and ftp.uu.net (directory vendor/MetaCard/1.2B5).

There is also a MetaCard mailing list.  To subscribe to the metacard-list,
send mail to [e-mail] with the following commands in the
body of the message:

      subscribe metacard-list firstname lastname
      quit


Replace "firstname lastname" with your name, not your e-mail address.



ezX User Interface Management System
Sunrise Software, International
170 Enterprise Center
Middletown, RI 02840
401-847-7868
email: [e-mail]



WKSH (Windowing Korn Shell):

   EXtensible Korn Shell (C language calling interface,
                          dynamic library loading, etc.)
   Motif or OpenLook API
   X Toolkit Intrinsics
   WKSH Convenience Functions
   Fast Learning and Prototyping Feature (ksh interpreter)


Contact:
   Acacia Computer,
   PO Box 4376,
   Warren, NJ 07059,
   Phone: [phone],
   Email: uunet!aca1

or

Computer Aid Inc, 1-(800)-444-WKSH

or

Consensys Corp, Europe: +(44)-734-833241 (Roger Chalke), +(44)0734-835391
(Fax), US: (416)-940-2903, (416)-940-2903 (Fax).


WKSH was developed by USL. Binaries are available through Acacia Computer for
SUNOS, Solaris, SCO ODT, Intel SVR4.0


Druid is a commercial product. It currently supports Motif1.1 and 4 unix
platforms: SPARC, HP 9000, RS6000, and SGI.

For further information contact: Mr. Fred Lee, Automated Systems (Pte)
Limited, 203 Henderson Road, #12-07/14, Henderson Industrial Park, Singapore
0315.  FAX: [phone]

Or: Dr. Gurminder Singh ([e-mail]), Institute of Systems Science,
National University of Singapore




-----------------------------------------------------------------------------
Subject: 33)  TOPIC: TEXT WIDGET

-----------------------------------------------------------------------------
Subject: 34) What is the difference between a XmTextField widget and a single
line XmText widget?

Answer: Their functionality is the same, but the XmTextField is designed to
give superior performance.  thanks to Ken Lee, [e-mail]


-----------------------------------------------------------------------------
Subject: 35)  Why does  pressing  <return> in a text widget do nothing?  This
happens using Motif 1.0 when I have a text widget inside a bulletin board (or
form) inside a dialog shell. (In Motif 1.1 it is fixed for both text and list
widgets.)

Answer: In single line mode, pressing the <return> key usually invokes the
activate() action, and in multi-line mode, the newline() action.  However,
whenever a widget is the child of a bulletin board widget which is the child
of a dialog shell, the bulletin board forces all of its children to translate
<return> to the bulletin board action Return() which is usually associated
with the default button of the dialog.  To restore the text actions of
activate() or newline(), you need to overide the Return() action of the
bulletin board.


        /* declarations */
        /* for a single line widget */
        char newTrans[] = "<Key>Return : activate()";
        /* for a multi line widget */
        char newTrans[] = "<Key>Return : newline()";
        XtTranslations transTable;

        /* in executable section */

        transTable = XtParseTranslationTable(newTrans);

        /* after creating but before managing text widget */

        XtOverrideTranslations(textWidget, transTable);


-----------------------------------------------------------------------------
Subject: 36)  When I add text to a scrolling text widget how can I get the new
text to show?

Answer: Use the call undocumented in Motif 1.0

        void XmTextShowPosition(w, position)
        Widget w;
        XmTextPosition position;

where the position is the number of characters from the beginning of the
buffer of the text to be displayed. If you don't know how many characters are
in the buffer, use another call undocumented in Motif 1.0

        position = XmTextGetLastPosition(w)


-----------------------------------------------------------------------------
Subject: 37)  Does the text widget support 16 bit character fonts?


[Last modified: November 92]

Answer: R5 has support for 16 bit character sets, and Motif 1.2 uses that.
Neither Motif 1.0 nor 1.1 support 16 bit sets.

-----------------------------------------------------------------------------
Subject: 38)  How can I stop the text widget from echoing characters typed?  I
need to turn off echo for password input.

Answer: Use the modifyVerifyCallback to tell when input is received. Set the
`doit' field in the XmTextVerifyCallbackStruct to False to stop the echo. In
Motif 1.0 this will cause a beep per character: Live with it, because at 1.1
you can turn it off.  Note that password hiding is inherently insecure in X -
someone may have an X grab on the keyboard and be reading all characters typed
in anyway.

Another solution often proposed is to set the foreground and background
colours to be the same, effectively hiding the text.  This has a major flaw:
someone may select the text (triple click the mouse to get the line), and then
paste the password into say an xterm with *different* foreground and
background colours.  This immediately shows the password.

-----------------------------------------------------------------------------
Subject: 39)  How can I replace characters typed with say a `*'?  I want to
replace input for password entry.

[Last modified: April 93]

Answer: In Motif 1.1 Use the modifyVerifyCallback to tell when input is
received.  Set text->ptr in the callback structure to '*'. This does not work
under 1.0 because of an oversight in which changes to this are ignored.  In
Motif 1.0, what you can do is set the doit flag to 'false' so the text is not
displayed. Then set a static boolean to True to prevent re-entrance.  Next
call XmTextReplace() to display your '*'.  then reset your re-entrance flag to
False.  XmTextReplace() will call the XmNmodifyVerify callback.  To prevent
getting into an infinite loop, you need the re-entrance flag.

The following program from Dan Heller illustrates this:

--------------
/* Written by Dan Heller.  Copyright 1991, O'Reilly && Associates.
 * This program is freely distributable without licensing fees and
 * is provided without guarantee or warranty expressed or implied.
 * This program is -not- in the public domain.  This program appears
 * in the Motif Programming Manual, O'Reilly Volume 6.
 */

/* passwd.c -- prompt for a passwd.  Meaning, all input looks like
 * a series of *'s.  Store the actual data typed by the user in
 * an internal variable.  Don't allow paste operations.  Handle
 * backspacing by deleting all text from insertion point to the
 * end of text.
 */
#include <Xm/Text.h>
#include <Xm/LabelG.h>
#include <Xm/RowColumn.h>
#include <ctype.h>

void check_passwd();
char *passwd; /* store user-typed passwd here. */

main(argc, argv)
int argc;
char *argv[];
{
    Widget        toplevel, text_w, rowcol;
    XtAppContext  app;

    toplevel = XtVaAppInitialize(&app, "Demos",
        NULL, 0, &argc, argv, NULL, NULL);

    rowcol = XtVaCreateWidget("rowcol",
        xmRowColumnWidgetClass, toplevel,
        XmNorientation, XmHORIZONTAL,
        NULL);

    XtVaCreateManagedWidget("Password:",
        xmLabelGadgetClass, rowcol, NULL);
    text_w = XtVaCreateManagedWidget("text_w",
        xmTextWidgetClass, rowcol, NULL);

    XtAddCallback(text_w, XmNmodifyVerifyCallback, check_passwd, NULL);
    XtAddCallback(text_w, XmNactivateCallback, check_passwd, NULL);

    XtManageChild(rowcol);
    XtRealizeWidget(toplevel);
    XtAppMainLoop(app);
}

void
check_passwd(text_w, unused, cbs)
Widget        text_w;
XtPointer     unused;
XmTextVerifyCallbackStruct *cbs;
{
    char *new;
    int len;

    if (cbs->reason == XmCR_ACTIVATE) {
        printf("Password: %s\n", passwd);
        return;
    }

    if (cbs->text->ptr == NULL) { /* backspace */
        cbs->endPos = strlen(passwd); /* delete from here to end */
        if (cbs->endPos <= 0) return; /* catch null passwd - Mark Scoville */
        passwd[cbs->startPos] = 0; /* backspace--terminate */
        return;
    }

    if (cbs->text->length > 1) {
        cbs->doit = False; /* don't allow "paste" operations */
        return; /* make the user *type* the password! */
    }

    new = XtMalloc(cbs->endPos + 2); /* new char + NULL terminator */
    if (passwd) {
        strcpy(new, passwd);
        XtFree(passwd);
    } else
        new[0] = NULL;
    passwd = new;
    strncat(passwd, cbs->text->ptr, cbs->text->length);
    passwd[cbs->endPos + cbs->text->length] = 0;

    for (len = 0; len < cbs->text->length; len++)
        cbs->text->ptr[len] = '*';
}


-----------------------------------------------------------------------------
Subject: 40)  How can I best add a large piece of text to a scrolled text
widget?  In some versions of Motif 1.0 even using XmTextSetString, it insists
on adding the text one line at a time, adjusting the scroll bar each time. It
looks awful and is slow.

Answer: If you don't have this problem, use XmTextSetString to set all of the
text in the widget.  If you do have this slowdown problem even using
XmTextSetString, unmanage the widget, add the text and then manage it again.
This may cause the window to blink, but you have to put up with that or switch
to a different version of Motif.

-----------------------------------------------------------------------------
Subject: 41)  How can I highlight text in the Text widget?

Answer: From: [e-mail] (Dan Heller)

If you don't need font or color changes, you can do all this using a Text
widget very easily [in Motif 1.1, anyway].

        loop() {
            pos = offset_of_pattern_in_text_widget(pattern, text_w);
            search_len = strlen(pattern);
            XmTextSetHighlight(text_w, pos, pos+search_len,
                        XmHIGHLIGHT_SELECTED);
        }


There are two choices for highlighting: reverse video (HIGHLIGHT_SELECTED) and
underlined (HIGHLIGHT_SECONDARY_SELECTED).  Be careful that your users won't
confuse your highlights with actual selections!

-----------------------------------------------------------------------------
Subject: 42)  How can I select all of the text in a widget programmatically?
So that some initial text is displayed, but anything typed replaces it.

Answer: XmTextSetSelection(Text1, 0, XmTextGetLastPosition(Text1), event-
>xbutton.time);

where Text1 is the widget in question (obviously) and event is some event that
triggered this call.  You can use XtLastTimestampProcessed( display) instead
of xbutton.time if you don't happen to have an event pointer handy.




-----------------------------------------------------------------------------
Subject: 43)  How can I change colours of text in the Text widget?  I want
some of the text in one colour, some in another.

Answer: You can't.  Text stores an ordinary string, and points where
`highlights' of various types begin and end.  These highlights are all the
control you have over components of the text.  See the previous question.


-----------------------------------------------------------------------------
Subject: 44)  How can I change the font of text in the Text widget?  I want
some of the text in one font, some in another.

Answer: You can't in Text (see the previous question).  If you wanted readonly
text, you could do it by using a label instead.  Label uses XmStrings, which
can contain multiple character sets in the one string.

-----------------------------------------------------------------------------
Subject: 45)  Is there an emacs binding for the text widget?

Answer: This set is due to Kee Hinckley ([e-mail]):

*XmText.translations: #override\n\
        Ctrl <Key>b:            backward-character()\n\
        Alt <Key>b:             backward-word()\n\
        Meta <Key>b:            backward-word()\n\
        Shift Alt <Key>b:       backward-word(extend)\n\
        Shift Meta <Key>b:      backward-word(extend)\n\
        Alt <Key>[:             backward-paragraph()\n\
        Meta <Key>[:            backward-paragraph()\n\
        Shift Alt <Key>[:       backward-paragraph(extend)\n\
        Shift Meta <Key>[:      backward-paragraph(extend)\n\
        Alt <Key><:             beginning-of-file()\n\
        Meta <Key><:            beginning-of-file()\n\
        Ctrl <Key>a:            beginning-of-line()\n\
        Shift Ctrl <Key>a:      beginning-of-line(extend)\n\
        Ctrl <Key>osfInsert:    copy-clipboard()\n\
        Shift <Key>osfDelete:   cut-clipboard()\n\
        Shift <Key>osfInsert:   paste-clipboard()\n\
        Alt <Key>>:             end-of-file()\n\
        Meta <Key>>:            end-of-file()\n\
        Ctrl <Key>e:            end-of-line()\n\
        Shift Ctrl <Key>e:      end-of-line(extend)\n\
        Ctrl <Key>f:            forward-character()\n\
        Alt <Key>]:             forward-paragraph()\n\
        Meta <Key>]:            forward-paragraph()\n\
        Shift Alt <Key>]:       forward-paragraph(extend)\n\
        Shift Meta <Key>]:      forward-paragraph(extend)\n\
        Ctrl Alt <Key>f:        forward-word()\n\
        Ctrl Meta <Key>f:       forward-word()\n\
        Ctrl <Key>d:            kill-next-character()\n\
        Alt <Key>BackSpace:     kill-previous-word()\n\
        Meta <Key>BackSpace:    kill-previous-word()\n\
        Ctrl <Key>w:            key-select() kill-selection()\n\
        Ctrl <Key>y:            unkill()\n\
        Ctrl <Key>k:            kill-to-end-of-line()\n\
        Alt <Key>Delete:        kill-to-start-of-line()\n\
        Meta <Key>Delete:       kill-to-start-of-line()\n\
        Ctrl <Key>o:            newline-and-backup()\n\
        Ctrl <Key>j:            newline-and-indent()\n\
        Ctrl <Key>n:            next-line()\n\
        Ctrl <Key>osfLeft:      page-left()\n\
        Ctrl <Key>osfRight:     page-right()\n\
        Ctrl <Key>p:            previous-line()\n\
        Ctrl <Key>g:            process-cancel()\n\
        Ctrl <Key>l:            redraw-display()\n\
        Ctrl <Key>osfDown:      next-page()\n\
        Ctrl <Key>osfUp:        previous-page()\n\
        Ctrl <Key>space:        set-anchor()\n


! If you'd like the Delete key to work like backspace instead of deleting
! backwards, add the following definition to the lines above.
!       <Key>osfDelete: delete-previous-character()\n\

! These aren't included because they could intefere with
| menu accelerators (or vice versa)
!       Alt <Key>p:             backward-paragraph()\n\
!       Meta <Key>p:            backward-paragraph()\n\
!       Shift Alt<Key>p:        backward-paragraph(extend)\n\
!       Shift Meta<Key>p:       backward-paragraph(extend)\n\
!       Alt <Key>w:             copy-clipboard()\n\
!       Meta <Key>w:            copy-clipboard()\n\
!       Ctrl Alt <Key>w:        cut-clipboard()\n\
!       Ctrl Meta <Key>w:       cut-clipboard()\n\
!       Alt <Key>y:             paste-clipboard()\n\
!       Meta <Key>y:            paste-clipboard()\n\
!       Alt <Key>f:             forward-word()\n\
!       Meta <Key>f:            forward-word()\n\
!       Alt <Key>n:             forward-paragraph()\n\
!       Meta <Key>n:            forward-paragraph()\n\
!       Shift Alt <Key>n:       forward-paragraph(extend)\n\
!       Shift Meta <Key>n:      forward-paragraph(extend)\n\
!       Shift Alt <Key>f:       forward-word(extend)\n\
!       Shift Meta <Key>f:      forward-word(extend)\n\
!       Alt <Key>d:             kill-next-word()\n\
!       Meta <Key>d:            kill-next-word()\n\
!       Alt <Key>h:             select-all()\n\
!       Meta <Key>h:            select-all()\n\

Similar sets of translations have been suggested by others.

-----------------------------------------------------------------------------
Subject: 46)  How can I use a file as the text source for a Text widget?

Answer: You can't do it directly like you can with the Athena Text widget.
Instead, read the text from the file into a string (all of it!) and then use
XmTextSetString.  Alternatively, read blocks of characters and add them at the
end of the text using XmTextInsertString.  The following is an excerpt from
Dan Heller's "file_browser.c":

    /* file_browser.c -- use a ScrolledText object to view the
     * contents of arbitrary files chosen by the user from a
     * FileSelectionDialog or from a single-line text widget.
     */

    ...
    struct stat statb;

    /* make sure the file is a regular text file and open it */
    if (stat(filename, &statb) == -1 ||
            (statb.st_mode & S_IFMT) != S_IFREG ||
            !(fp = fopen(filename, "r"))) {
        if ((statb.st_mode & S_IFMT) == S_IFREG)
            perror(filename); /* send to stderr why we can't read it */
        else
            fprintf(stderr, "%s: not a regular file0, filename);
        XtFree(filename);
        return;
    }

    /* put the contents of the file in the Text widget by allocating
     * enough space for the entire file, reading the file into the
     * allocated space, and using XmTextFieldSetString() to show the file.
     */
    if (!(text = XtMalloc((unsigned)(statb.st_size+1)))) {
        fprintf(stderr, "Can't alloc enough space for %s", filename);
        XtFree(filename);
        fclose(fp);
        return;
    }

    if (!fread(text, sizeof(char), statb.st_size+1, fp))
        fprintf(stderr, "Warning: may not have read entire file!0);

    text[statb.st_size] = 0; /* be sure to NULL-terminate */

    /* insert file contents in Text widget */
    XmTextSetString(text_w, text);




-----------------------------------------------------------------------------
Subject: 47)  How can put Text in overstrike mode instead of insert?

Answer: There is no direct way. This was posted by Edmond Pitt
([e-mail]) The correct answer to the question is to put the following
in a modifyVerify callback, where 'mvcb' is the XmTextVerifyCallbackStruct,
and 'overstriking' is defined by you:

    if (overstriking && mvcb->text->length == 1)
    {
        _XmTextDisableRedisplay(w,FALSE);
        XtCallActionProc(w,"delete-next-character",mvcb->event,0);
        _XmTextEnableRedisplay(w);
    }

_XmText{Dis,En}ableRedisplay() are XmText{Dis,En}ableRedisplay() in 1.0, but
X11R3 has no XtCallActionProc() anyway. For this environment you need my 1.0.3
Text widget patches posted last year & available on request.


-----------------------------------------------------------------------------
Subject: 48)  How can I make the Delete key do a backspace?

Answer: Put this in your .Xdefaults

    *XmText.translations: #override <Key>osfDelete: delete-previous-character()


-----------------------------------------------------------------------------
Subject: 49)  TOPIC: LIST WIDGET

-----------------------------------------------------------------------------
Subject: 50) Should I create an XmList widget as a child of automatic
XmScrolledWindow or use the XmCreateScrolledList() convenience function?

Answer: With most implementations, the convenience function use internal hooks
to give somewhat better scrolling performance.  thanks to Ken Lee,
[e-mail]

-----------------------------------------------------------------------------
Subject: 51)  How do I best put a new set of items into a list?

Answer: Set the new list count and list by XtSetArgs and install them by
XtSetValues.

    XmString list[SIZE];
    int list_size;

    XtSetArg (args[n], XmNitemCount, list_size); n++;
    XtSetArg (args[n], XmNitems, list); n++;
    XtSetValues (w, args, n);

Each time the list is reset by this the old contents are freed by the widget
and the new supplied list is copied.  Do *not* free the old list of items
yourself as this would result in the space being freed twice.  It is not
necessary to remove the items one at a time, nor to "zero" out the list first.

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Subject: 52)  Can I have strings with different fonts in a list?

Answer: Yes. The strings are XmStrings. Each one can be created using a
different character set using a different font.


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Subject: 53)  Can I get a bitmap to show in a list item like I can in a Label?
I want to place a bitmap along with some normal text in my list items.

Answer: No. The list contains XmStrings, and these only allow text in various
character sets. The workaround is to define your font containing the icons you
want. Then you can create a fontlist containing your icon font and the font
you want the text in, and then make your items multi-segment XmStrings where
the first segment contains the code of the icon you want with a charset that
matches the icon font in your fontlist and the second segment with a charset
matching the text font.


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Subject: 54)  Can I have items with different colours in a list?

Answer: No.  The list contains XmStrings, and these only allow text in various
character sets. Since the items are XmStrings, you can already change the font
of an item by replacing it with an item with the same text and a different
charset tag.  Adding support for color would require modification of the
internal data structure in XmList as well as modification to the drawing
routines.  A possible workaround is to use a rowcolumn of buttons which can be
individually set.  However, you would have to do all list functionality
yourself.


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Subject: 55)  Can I grey out an item in a list?  I want to make insensitive
items in a list so that they cannot be selected.

Answer:

From W. Scott Meeks of OSF:

Unfortunately, you can't do it directly since the list items aren't individual
widgets.  We've had other requests for this technology, but it didn't make the
cut for 1.2; it should be in some future release.

However, you can probably fake it in your application with some difficulty.
First, a list item is an XmString, so you can specify a different charset for
the item than for other items in the list and then specify a font in the
list's fontlist that matches the charset and gives you the visual you want.
The next problem is making the item unselectable.  One idea would be to have
the application keep track of the insensitive items and the items currently
selected.  Then you would set up a selection callback that when called would
check the item selected against the list of insensitive items and if the
selected item matched would deselect that item and reselect the previously
selected items.  Otherwise it would just update the application's list of
selected items.  The major drawback with this approach is that you'll get
flashing whenever the list selects an item and your application immediately
de-selects.  Unfortunately I can't think of a way around this without mucking
with the list internals.

Another alternative suggested is to use instead a column of say read only text
widgets which you can make insensitive.

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Subject: 56)  Can I have multi-line items in a list?
[Last modified: August 92]

Answer: Motif 1.0 and 1.1 both have problems with multi-line items in a list.
They should work okay in Motif 1.2.

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Subject: 57)  How can I tell the position of selected items in a list?

[Last modified: Oct 92]

Answer: From  W. Scott Meeks:

1) All XmList selection callbacks get an XmListCallbackStruct which includes
the item selected and its position.  In addition, the multiple and extended
selection callbacks also get a list of the selected items.  This approach
requires that your application saves this information if you need it outside
of the immediate callback.

2) At any time you can XtGetValues the XmNselectedItems and
XmNselectedItemCount resources.  The problem with this approach is that
identical items may or may not show up in multiple times in this list and the
position in the selectedItems list may not relate directly to the position in
the items list.

3) You can call XmListGetSelectedPos on the list widget.  This will return a
list of the positions of all selected items.

-----------------------------------------------------------------------------
Subject: 58)  TOPIC: FILE SELECTION BOX WIDGET

-----------------------------------------------------------------------------
Subject: 59)  What is libPW.a and do I need it?  My manual says I need to link
in libPW.a to use the File Selection Box.  I can't find it on my system.

Answer: The libPW.a is the Programmers Workbench library which is an ATT
product not included in Berkeley based systems, hence it is not found in SunOS
or Ultrix, but is found on HP-UX (a Berkeley/ATT hybrid which chose ATT in
this case).  It contains the regex(3) routines (regcmp, regex).  Some systems
which don't have these in the libc.a need to link with -lPW.  Some systems
which have the regex(3) routines in there also have the libPW.a.  If you have
regex(3) in libc, and it works, don't link with libPW.  If you don't have
regex(3) in libc, and you don't have a libPW, then check some sites on the net
for public domain replacements (several exist), or call your vendor.

In most versions of Motif (see the doco), you can compile FileSB.c with
-DNO_REGEX if you don't have it.

-----------------------------------------------------------------------------
Subject: 60)  What are these compile errors: Undefined symbol _regcmp and
_regex?

Answer: You need to link in the libPW library - see previous question.


-----------------------------------------------------------------------------
Subject: 61)  What's wrong with the Motif 1.0 File Selection Box?  I can't set
the directory, change the directory or get the file mask to work.

Answer: The 1.0 File Selection Box is broken, and these don't work.  They
weren't fixed until Motif 1.04.  Use these later versions of 1.0 or switch to
Motif 1.1 where it changed a lot.

Joe Hildebrand has a work-around for some of this: Before popping up an
XmFileSelectionDialog, change to the directory you want.  When a file is
selected, check if it is a directory, so that we can change to it.  i.e.

static void show_file_box_CB(w, client_data, call_data)
   Widget               w;
   Widget               client_data;
   XmAnyCallbackStruct  *call_data;
{
   chdir("/users/hildjj/files");
   XtManageChild(client_data);
}

static void val_save(w, client_data, call_data)
   Widget       w;
   Widget       client_data;
   XmSelectionBoxCallbackStruct *call_data;
{
   struct stat buf;  /* struct stat is defined in stat.h */
   char *filename;

   /* get the file name from the FileSelectionBox */
   filename = SmX(call_data->value);

   /* get the status of the file named filename, and put it into buf */
   if (!stat(filename, &buf))
   {
      /* if it's a directory */
      /* if it's a directory */
      if(S_ISDIR(buf.st_mode))
      {
         /* change to that directory, and update the FileSelectionBox */
        chdir(filename);
        XmFileSelectionDoSearch(w, NULL);
      }
      else
         /* if it's a regular file */
         if(S_ISREG(buf.st_mode))
            /* ask if it should be overwritten */
            XtManageChild(valbox);
         else
            /* it's another kind of file.  What type, i can't think of,
               but it might happen */
            pop_up_error_box(client_data, "Error saving file");
   }
   else  /* we couldn't get the file status */
   {
      /* if it's because the file doesn't exist, we're golden */
      if (errno == ENOENT)
         save_file();
      else   /* there is some other problem getting the status.
                e.g. bad path */
         pop_up_error_box(client_data, "Error saving file");
   }
}

this still doesn't implement the file masking stuff.


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END OF PART TWO
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