Volume 6A: Motif Programming Manual

keysym. This function allows an application that overrides the default XtKeyProc to handle Motif's virtual key

bindings. See Section #seventspec in Chapter 2, The Motif Programming Model, for more information on virtual

bindings. The new XmChangeColor() routine changes the foreground color, shadow colors, and select color for a

widget based on a background color. The XmNdarkThreshold, XmN-foregroundThreshold, and

XmNlightThreshold resources of the Screen object allow the application or the user to set values that affect the

default color calculation algorithm. The values for these resources indicate the levels of perceived brightness (between

0 and 100) that distinguish between a light color and a dark color. The XmNforegroundThreshold value is used

in calculating the default foreground and highlight colors, while the other two resources are used in calculating the

default shadow and select colors. See Section #scolor for a discussion of color resources in Motif. An application can

use the new XmWidgetGetBaselines() routine to get the position of the text baseline in a widget, while

XmWidgetGetDisplayRect() can be used to get the size and position of the bounding box for the widget. These

routines provide information that is useful in laying out and aligning components in an interface.

4.5.2 Specific Widget Changes

Motif 1.2 also introduces a number of new features, including resources and callback routines, for individual widget

classes. In Motif 1.2, the Frame widget can have two children: a work area and a title. The Frame draws a border

around its work area child and adds space for a title if one is specified. The XmNchildType constraint resource

specifies whether a child is the work area or the title. This resource can have either the value

XmFRAME_WORKAREA_CHILD or XmFRAME_TITLE_CHILD. The XmNchildHorizontalAlignment,

XmNchildHorizontalSpacing, and XmNchildVerticalAlignment constraint resources control the

positioning of the title child. For more information on these resources, see Section #sframe in Chapter 8, Manager

Widgets. The Label widget functions as a drag source for drag and drop, as described in Chapter 18, Drag and Drop.

The ProcessDrag() action routine, which is bound to the second mouse button, handles this functionality. The

List widget provides the following new functions for managing list items:

XmListAddItemUnselected()

XmListDeletePositions()

XmListGetKbdItemPos()

XmListPosSelected()

XmListPosToBounds()

XmListReplaceItemsPosUnselected()

XmListReplaceItemsUnselected()

XmListReplacePositions()

XmListSetKbdItemPos()

XmListUpdateSelectedList()

XmListYToPos()

For more information on these routines, see Chapter 12, The List Widget, and the appropriate reference pages in

Volume Six B, Motif Reference Manual.

When a List widget is set insensitive, it provides visual indication by greying out all of its items. The default value of

the XmNvisibleItemCount resource is now set dynamically, based on the item count and the height of the List.

The List widget functions as a drag source for drag and drop, as described in Chapter 18, Drag and Drop. The

ListProcessDrag() action routine, which is bound to the second mouse button, handles this functionality. The

List also has a ListCopyToClipboard() action routine for copying the selected items to the clipboard, as well as

a ListScrollCursorVertically() routine for scrolling the cursor vertically based on a y−position. The

MessageBox widget supports the addition of a MenuBar child, a work area child, and multiple PushButton children.

The XmNdialogType resource can also be set to the value XmDIALOG_TEMPLATE to create a MessageBox that

can be used as a template for creating a custom dialog. Section #smoddialog in Chapter 7, Custom Dialogs, describes

the template dialog in more detail. The PanedWindow defines a new constraint resource, XmNpositionIndex, for

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specifying the position of a child widget in the PanedWindow's list of children. The children are positioned vertically

in the PanedWindow according to this list. The list of children does not include the Sashes. A value of 0 indicates the

beginning of the list, while XmLAST_POSITION places the child at the end of the list. The RowColumn widget

provides a new resource for controlling the alignment of its children. The XmNentryVerticalAlignment

resource controls the vertical positioning of children that are subclasses of Label, LabelGadget, and Text, as described

in Section #srowcolumn in Chapter 8, Manager Widgets.

The RowColumn widget also defines the XmNpositionIndex constraint resource for specifying the position of a

child widget in the RowColumn's list of children. The children are positioned in the RowColumn according to this list.

A value of 0 indicates the beginning of the list, while XmLAST_POSITION places the child at the end of the list.

The XmNtearOffModel resource of the RowColumn widget controls tear−off functionality in Motif menus. The

widget also defines the XmNtearOffMenuActivateCallback and

XmNtearOffMenuDeactivateCallback callback routines for performing any special processing that is

necessary for handling tear−off menus. Tear−off functionality is described in detail in Section #stearoff in

Chapter 15, Menus. When a ScrollBar is set insensitive, it provides a visual indication of this state by dimming itself.

The ScrollBar also has new action routine, CancelDrag(), that cancels the current slider drag. When the user

presses the ESCAPE key while the slider is being dragged, the action is invoked. In Motif 1.2, the ScrolledWindow

has a new callback that supports keyboard traversal. The XmNtraverseObscuredCallback is invoked when the

user attempts to traverse to a widget that is not visible in a ScrolledWindow. An application can use this callback to

make a widget visible in a ScrolledWindow so that the widget can receive the input focus. The

XmScrollVisible() routine makes an obscured child of a ScrolledWindow visible, while

XmGetVisibility() determines whether or not a widget is visible. See Section #sswtrav in Chapter 9,

ScrolledWindows and ScrollBars, for more information on keyboard traversal in ScrolledWindows.

The SelectionBox and FileSelectionBox widgets now support the addition of a MenuBar child and multiple

PushButton children in addition to the work area child that was supported in Motif 1.1. The new

XmNchildPlacement resource controls the location of the work area child, as described in Section #smodseldlg in

Chapter 7, Custom Dialogs.

The Text and TextField widgets have a number of new resources and callback routines that support wide−character

strings. These changes have been made for internationalization purposes and are described in Section #stexti18n in

Chapter 14, Text Widgets. The widgets function as drag sources and drop sites for drag and drop, as described in

Chapter 18, Drag and Drop.

The insertion position in the Text and TextField widgets is marked by an I−beam cursor. The destination cursor now

follows the insertion cursor, so it is no longer drawn independently as a caret (^). When a Text or TextField widget is

set insensitive, it provides a visual indication of this state by greying out its text and its insertion cursor. Both the Text

and TextField widgets provide the toggle−overstrike() action routine for switching between insert and

overstrike modes. The Text widget also provides the scroll−cursor−vertically() action to scroll the cursor

based on a y position. When the user moves the pointer outside of a Text widget while selecting text, the widget

continues selecting text by scrolling automatically after a time delay.

The new XmTextDisableRedisplay() and XmTextEnableRedisplay() routines provide a way to control

visual updating in a Text widget. The XmTextFindString(), XmTextGetSubstring(), and

XmTextFieldGetSubstring() functions make string manipulation easier. For more information on these

routines, see the appropriate reference pages in Volume Six B, Motif Reference Manual. The TextField widget also

has an XmNfocusCallback in Motif 1.2. The performance of scrolling in the ScrolledText object has been

improved in Motif 1.2. One unfortunate side−effect of this improvement is that it introduces a new data structure,

which means that subclasses of the Motif 1.1 Text widget may break under Motif 1.2.

If XmNfillOnSelect is explicitly set to True when XmNindicatorOn is False, the background of the

ToggleButton is set to the XmNselectColor when the button is on.

The VendorShell provides the XmNaudibleWarning resource to specify whether or not an audible cue

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