The LiteClue Widget

1. Copyright

Copyright 1995 Computer Generation, Inc. You may reproduce this document without charge provided the copyright and disclaimer notices appear. The software described in this document is copyrighted under separate terms. See the source code available at

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall Computer Generation, inc. nor the author(s) be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

The author welcomes comments and suggestions.
Gary Aviv
Computer Generation, Inc.,

Thanks to contributers:: J Satchell, Eric Marttila, Addy Klos.

If you wish to be on an Emailing list regarding this or other CGI widgets, please send a request to the above address. You will be notified when this or other widgets are upgraded or when new widgets become available.

Updated: 30 October 1998

2. Introduction

LiteClue is a widget which pops a one line help message when the user passes the pointer over another "watched" widget. This is known by various names in the industry such as hints, clues, tips, bubble help and balloon help.

Clues are particularly helpful for push buttons that contain graphic pixmaps rather than text. They obviate the need to place text within graphics in the button which creates internationalization problems. A clue may be attached to virtually any widget that has a window (no gadgets). LiteClue works with Motif but does not require it.

None of this affects the behaviour of the watched widget itself. LiteClue monitors enter and leave events of the watched widget's window passively.

LiteClue relies on EnterNotify and LeaveNotify events for the the widgets it is watching. This will normally prevent clues from poping up when the watched widgets are insensitive. See the function XcgLiteClueDispatchEvent for a way to bypass this limitation.

LiteClue inherits behaviour and ewsources from OverrideShell.

The class pointer is xcgLiteClueWidgetClass.

The class name is xcgLiteClue.

3. Version Information

Version 1.2

  1. R4 back compatibility
  2. Delay before pop up of help; XcgNwaitperiod resource (default 500 ms).
  3. Button press in watched widget pops down help.

Version 1.3

  1. Support of cancelWaitPeriod resource. this is the period after a help popdown occurs in which the normal waitPeriod is suspended for the next popup.
  2. minor fixes

Version 1.4

  1. Support for clues on insensitive widgets. See XcgLiteClueDispatch function below.

Version 1.5

  1. Position the clue above the watched widget or move the clue right or left to make it visible if it would otherwise be off the screen.

4. Distribution Kit

The source distribution kit contains the following files:

LiteClue.c LiteClue.h LiteClueP.h
The LiteClue widget source code
A small demonstration program
an Imake file.
a command file for building under DEC VMS
LiteClue.html LiteClue.txt
Documentation in HTML, plain text and PostScript formats

LiteClue has been compiled successfully on NCR MPRAS, Digital OSF/Unix, ULTRIX (XR4), Linux, VMS and probably many others.

To build the test program:


For VMS, see the file BUILD.COM.

LiteClue is designed for X11R4 or higher. It checks XtSpecificationRelease at compile time. When compiled for X11R5 or higher, it uses font sets which gives it good internationalization support (see Section 10 below). However, you can also force it to use font structs instead by setting a compile time variable (see make file).

When using font sets, you may get the message:

Warning: Missing charsets in String to FontSet conversion
Warning: Unable to load any usable fontset

which means that your locale does not support the font's character sets. On many machine, the default C locale does not allow 8-bit characters or the iso88591 character set required by the default fonts. Fix this by setting your LANG environment variable. For example, on HP-UX in the US you set:


5. Resources

LiteClue adds the following resources to those it inherits. The resource class is obtained by replacing the N by a C in the resource name (eg: XtNfontSet is the name XtNfontSet is the class. The access types are C (resource may be set at create time), S (may be se using XtSetValues), or G (may be read using XtGetValues).

Type = FontSet, Default = "-adobe-new century schoolbook-bold-r-normal-*-12-*, Access = CG
The font used to display the clue. For Xt Release 4 or less, the resource name XtNfont and the type is FontStruct.
Type = Pixel, Default = "black", Access = CSG
The color used to render the clue text
Type = Integer, Default = 500, Access = CSG
The delay from the time the pointer enters the watched widget until the help is popped up in milliseconds.
Type = Integer, Default = 2000, Access = CSG
The period (in milliseconds) after a help popdown occurs in which the normal waitPeriod is suspended. If the pointer should re-enter a watched widget during this period help pops up immediately rather than waiting waitPeriod milliseconds.

The background color resource XtNbackground of the clue popup is inherited from OverrideShell.

6. Callbacks

LiteClue adds no new callbacks over those it inherits.

7. Translations

LiteClue has no translations.

8. LiteClue API

LiteClue contains the following functions that control the widget behaviour.

8.1 XcgLiteClueAddWidget -- Add a widget to be watched.

A widget will be added to the LiteClue watched list. Clues are given for sensitive watched widgets when the pointer enters its window. If the widget is already watched, the passed text replaces its current clue text. If text is null, the widget is still added, if it is not already in the list, but no clue will appear. Text may be specified with XcgLiteClueAddWidget in a subsequent call. When text is null and the widget is already in the list, its text is not changed. When a widget will is added to the watched list, it automatically becomes sensitive. Otherwise, its sensitivity is not changed. A watched widget which is not sensitive retains its context but clues are suppressed. None of this affects the behaviour of the watched widget itself. LiteClue monitors enter and leave events of the watched widget's window passively.

void XcgLiteClueAddWidget(Widget w, Widget watch, char * text, int size, int option )

LiteClue widget
the widget for which clues will be given
pointer to buffer containing text. Must be null terminated
size of text, if 0, it will be computed (strlen)
option mask - must be zero


8.2 XcgLiteClueDeleteWidget -- Delete a widget that is watched.

A widget is deleted from the watched list and its resources are freed. LiteClue is no longer given for the widget. If the widget is not watched, nothing is done. None of this affects the behaviour of the watched widget itself, just whether a clue is poped for the widget.

void XcgLiteClueDeleteWidget(Widget w, Widget watch)

LiteClue widget
the widget to remove from watched list


8.3 XcgLiteClueSetSensitive - Enable/disable clues for watched widget.

When a watched widget is sensitive, a clue is poped up when the pointer enters its window. When a watched widget is insensitive, the widget is retained in the watched list but no clue is poped. The sensitivity of a watched widget relative to clues is set or reset by this function. The Xt sensitivity of the watched widget is not altered by this function.

void XcgLiteClueSetSensitive(Widget w, Widget watch, Boolean sensitive)

LiteClue widget
the widget to alter sensitivity
True - restore sensitivity
False - make insensitivity


8.4 XcgLiteClueGetSensitive - Get sensitivity setting for watched widget.

When a watched widget is sensitive, a clue is poped up when the pointer enters its window. When a watched widget is insensitive, the widget is retained in the watched list but no clue is poped. The sensitivity state of a watched widget relative to clues is returned by this function. The Xt sensitivity of a widget is a totally independent concept.

Boolean XcgLiteClueGetSensitive (Widget w, Widget watch)

LiteClue widget
the widget for which to get sensitivity state. If NULL first watched widget is used. If there are no watched widgets, False is returned.


True - watched widget is sensitive
False - watched widget is not sensitive

8.5 XcgLiteClueDispatchEvent -- Dispatch event from main X event loop

This function may be used to enable clues for insensitive watched widgets. Normally, XtAppMainLoop (which calls XtDispatchEvent) will not deliver EnterNotify and LeaveNotify events to widgets that are not sensitive (XtSetSensitive). This prevents clues from poping up for these widgets. To bypass this limitation, you can break out XtAppMainLoop and add a call to XcgLiteClueDispatchEvent ass follows:

MyXtAppMainLoop(XtAppContext app)
    XEvent event;
    for (;;) {
        XtAppNextEvent(app, &event);
	XcgLiteClueDispatchEvent(w, event) ;

Boolean XcgLiteClueDispatchEvent (Widget w, XEvent *event)

LiteClue widget
received event, normally from call to XtAppNextEvent.


- event was dispatched to non-sensitive watched widget.
- not a EnterNotify or LeaveNotify event or window in event is not a non-sensitive watched widget.

9. Sample Use

Since LiteClue is a shell widget , you make an instance of the shell as in this example:

	Widget liteClue, toplevel ;
  	toplevel = XtVaAppInitialize(&AppContext,
	liteClue = XtVaCreatePopupShell( "LiteClue_shell",
		xcgLiteClueWidgetClass, toplevel, ..., NULL);

If you want to change the font used by LiteClue, you could add the fontSet resource at create time as in:

#define RES_CONVERT( res_name, res_value) \
       XtVaTypedArg, (res_name), XmRString, (res_value), strlen(res_value) + 1

	liteClue = XtVaCreatePopupShell( "LiteClue_shell",
		xcgLiteClueWidgetClass, toplevel,
		 RES_CONVERT(XtNfontSet, \
			"-adobe-new century schoolbook-bold-r-normal-*-18-*"),

You need only create a single instance of the widget for the application. To attach help to a widget (usually a push button) use the function XcgLiteClueAddWidget (Section 8.1) as in:

	button_widg = XtVaCreateManagedWidget("Button1", xmPushButtonWidgetClass,
	XcgLiteClueAddWidget(liteClue, button_widg,  "Help Message", 0, 0);

In order to enable clues for insensitive widgets you will need to replace the standard call to XtAppMainLoop with the code as illustrated in the function XcgLiteClueDispatchEvent.

10. Internationalization

The LiteClue widget is designed to allow the display of internationalized text. This has been tested on a limited basis with Japanese.

In order to make use of internationalization, you must have support in your operating system for the desired locale and must have the needed fonts. In some cases, you may use the X provided locale support instead. At initialization, you should have code that looks something like:

	if (setlocale(LC_ALL,"") == NULL)
		fprintf(stderr, "LiteCluetest: Can't set locale\n");
	if (!XSupportsLocale())
		fprintf(stderr, "LiteCluetest: X does not support locale\n");
		setlocale(LC_ALL,NULL) ;
	if (XSetLocaleModifiers("") == NULL)
		fprintf(stderr, "LiteCluetest: Can't XSetLocaleModifiers\n");

If you need the X locale package, add the following:

	#define X_LOCALE
	#include <X11/Xlocale.h>

LiteClue makes use of the XR5 Font Set technology. All font resources are converted to Font Sets. For example, for Japanese you will need three fonts for each font set:

*XcgLiteClue.fontSet: \
-adobe-new century schoolbook-medium-r-normal-*-14-*,\

Finally, you must set the environment symbol LANG to the appropriate locale. For Japanese, one possibility is "LANG=ja_JP.eucJP".
LiteClue Widget