XmCascadeButton(3)

NAME
XmCascadeButton — The CascadeButton widget class

SYNOPSIS

#include <Xm/CascadeB.h>

DESCRIPTION

CascadeButton links two menu panes or a MenuBar to a menu pane.

It is used in menu systems and must have a RowColumn parent with its XmNrowColumnType resource set to XmMENU_BAR, XmMENU_POPUP or XmMENU_PULLDOWN.

It is the only widget that can have a Pulldown menu pane attached to it as a submenu. The submenu is displayed when this widget is activated within a MenuBar, a PopupMenu, or a PulldownMenu. Its visuals can include a label or pixmap and a cascading indicator when it is in a Popup or Pulldown menu pane; or it can include only a label or a pixmap when it is in a MenuBar. The positioning of the PulldownMenu with respect to the CascadeButton depends on the XmNlayoutDirection resource of the MenuShell.

The default behavior associated with a CascadeButton depends on the type of menu system in which it resides. By default, BSelect controls the behavior of the CascadeButton. In addition, BMenu controls the behavior of the CascadeButton if it resides in a PopupMenu system. The actual mouse button used is determined by its RowColumn parent. BMenu also performs the BSelect actions in all types of menu systems.

A CascadeButton's visuals differ from most other button gadgets. When the button becomes armed, its visuals change from a 2-D to a 3-D look, and it displays the submenu that has been attached to it. If no submenu is attached, it simply changes its visuals.

When a CascadeButton within a Pulldown or Popup menu pane is armed as the result of the user moving the mouse pointer into the widget, it does not immediately display its submenu. Instead, it waits a short amount of time to see if the arming was temporary (that is, the user was simply passing through the widget), or whether the user really wanted the submenu posted. This time delay is configurable using XmNmappingDelay.

CascadeButton provides a single mechanism for activating the widget from the keyboard. This mechanism is referred to as a keyboard mnemonic. If a mnemonic has been specified for the widget, the user may activate the CascadeButton by simply typing the mnemonic while the CascadeButton is visible. If the CascadeButton is in a MenuBar and the MenuBar does not have the focus, the MAlt modifier must be pressed with the mnemonic. Mnemonics are typically used to interact with a menu using the keyboard interface.

If the Cascadebutton is in a Pulldown or Popup menu pane and there is a submenu attached, the XmNmarginBottom, XmNmarginLeft, XmNmarginRight, and XmNmarginTop resources may enlarge to accommodate XmNcascadePixmap. XmNmarginWidth defaults to 6 if this resource is in a MenuBar; otherwise, it takes Label's default, which is 2.

CascadeButton uses the XmQTmenuSystem and XmQTspecifyRenderTable traits.

  Classes

CascadeButton inherits behavior, resources, and traits from Core, XmPrimitive, and XmLabel classes.

The class pointer is xmCascadeButtonWidgetClass.

The class name is XmCascadeButton.

  New Resources

The following table defines a set of widget resources used by the programmer to specify data. The programmer can also set the resource values for the inherited classes to set attributes for this widget. To reference a resource by name or by class in a .Xdefaults file, remove the XmN or XmC prefix and use the remaining letters. To specify one of the defined values for a resource in a .Xdefaults file, remove the Xm prefix and use the remaining letters (in either lowercase or uppercase, but include any underscores between words). The codes in the access column indicate if the given resource can be set at creation time (C), set by using XtSetValues (S), retrieved by using XtGetValues (G), or is not applicable (N/A).

XmNactivateCallback
    Specifies the list of callbacks that is called when the user activates the CascadeButton widget and there is no submenu attached to pop up. The activation occurs when a mouse button is released or when the mnemonic associated with the widget is typed. The specific mouse button depends on information in the RowColumn parent. The reason sent by the callback is XmCR_ACTIVATE.

XmNcascadePixmap
    Specifies the cascade pixmap displayed on one end of the widget when a CascadeButton is used within a Popup or Pulldown menu pane and a submenu is attached. The Label class resources XmNmarginBottom, XmNmarginLeft, XmNmarginRight, and XmNmarginTop may be modified to ensure that room is left for the cascade pixmap. The default cascade pixmap is an arrow pointing to the side of the menu where the submenu will appear. The positioning of the cascade pixmap to either the left of right of the widget, and the direction of the arrow, depend on the XmNlayoutDirection resource of the MenuShell.

XmNcascadingCallback
    Specifies the list of callbacks that is called just prior to the mapping of the submenu associated with CascadeButton. The reason sent by the callback is XmCR_CASCADING.

XmNmappingDelay
    Specifies the amount of time, in milliseconds, between when a CascadeButton becomes armed and when it maps its submenu. This delay is used only when the widget is within a Popup or Pulldown menu pane. The value must not be negative.

XmNsubMenuId
    Specifies the widget ID for the Pulldown menu pane to be associated with this CascadeButton. The specified menu pane is displayed when the CascadeButton becomes armed. The menu pane must have been created with the appropriate parentage depending on the type of menu used. See XmCreateMenuBar(3), XmCreatePulldownMenu(3), and XmCreatePopupMenu(3) for more information on the menu systems.

  Inherited Resources

CascadeButton inherits behavior and resources from the superclasses described in the following tables. For a complete description of each resource, refer to the reference page for that superclass.

  Callback Information

A pointer to the following structure is passed to each callback:

typedef struct
{
        int reason;
        XEvent * event;
} XmAnyCallbackStruct;

reason
    Indicates why the callback was invoked

event
    Points to the XEvent that triggered the callback or is NULL if this callback was not triggered due to an XEvent

  Translations

XmCascadeButton includes translations from XmPrimitive. XmCascadeButton includes the menu traversal translations from XmLabel.

Note that altering translations in #override or #augment mode is undefined.

The following list describes the translations for a CascadeButton in a MenuBar. The following key names are listed in the X standard key event translation table syntax. This format is the one used by Motif to specify the widget actions corresponding to a given key. A brief overview of the format is provided under VirtualBindings(3). For a complete description of the format, please refer to the X Toolkit Instrinsics Documentation.

<EnterWindow>Normal:
    MenuBarEnter()

<LeaveWindow>Normal:
    MenuBarLeave()

<Btn2Down>:
    ProcessDrag()

c<BtnDown>:
    MenuButtonTakeFocusUp()

c<BtnUp>:
    MenuButtonTakeFocusUp()

~c<BtnDown>:
    MenuBarSelect()

~c<BtnUp>:
    DoSelect()

:<Key><osfSelect>:
    KeySelect()

:<Key><osfActivate>:
    KeySelect()

:<Key><osfHelp>:
    Help()

:<Key><osfCancel>:
    CleanupMenuBar()

~s<Key>Return:
    KeySelect()

~s<Key>space:
    KeySelect()

The following list describes the translations for a CascadeButton in a PullDown or Popup MenuPane. In a Popup menu system, <Btn3> also performs the <Btn1> actions.

<EnterWindow>:
    DelayedArm()

<LeaveWindow>:
    CheckDisarm()

<Btn2Down>:
    ProcessDrag()

c<BtnDown>:
    MenuButtonTakeFocus()

c<BtnUp>:
    MenuButtonTakeFocusUp()

~c<BtnDown>:
    StartDrag()

~c<BtnUp>:
    DoSelect()

:<Key><osfSelect>:
    KeySelect()

:<Key><osfActivate>:
    KeySelect()

:<Key><osfHelp>:
    Help()

:<Key><osfCancel>:
    CleanupMenuBar()

~s<Key>Return:
    KeySelect()

~s<Key>space:
    KeySelect()

  Action Routines

The XmCascadeButton action routines are

CleanupMenuBar():
    In a MenuBar, disarms the CascadeButton and the menu and, when the shell's keyboard focus policy is XmEXPLICIT, restores keyboard focus to the widget that had the focus before the menu was entered.

    In a toplevel Pulldown MenuPane from a MenuBar, unposts the menu, disarms the MenuBar CascadeButton and the MenuBar, and, when the shell's keyboard focus policy is XmEXPLICIT, restores keyboard focus to the widget that had the focus before the MenuBar was entered. In other Pulldown MenuPanes, unposts the menu.

    In a Popup MenuPane, unposts the menu and, when the shell's keyboard focus policy is XmEXPLICIT, restores keyboard focus to the widget from which the menu was posted.

DoSelect():
    Calls the callbacks in XmNcascadingCallback, posts the submenu attached to the CascadeButton and enables keyboard traversal within the menu. If the CascadeButton does not have a submenu attached, this action calls the callbacks in XmNactivateCallback, activates the CascadeButton, and unposts all posted menus in the cascade.

Help():
    Unposts all menus in the menu hierarchy and, when the shell's keyboard focus policy is XmEXPLICIT, restores keyboard focus to the widget that had the focus before the menu system was entered. Calls the callbacks for XmNhelpCallback if any exist. If there are no help callbacks for this widget, this action calls the help callbacks for the nearest ancestor that has them.

KeySelect():
    Calls the callbacks in XmNcascadingCallback, and posts the submenu attached to the CascadeButton if keyboard traversal is enabled in the menu. If the CascadeButton does not have a submenu attached, this action calls the callbacks in XmNactivateCallback, activates the CascadeButton, and unposts all posted menus in the cascade.

MenuBarSelect():
    Unposts any menus posted by the parent menu. Arms both the CascadeButton and the MenuBar, posts the associated submenu, and enables mouse traversal. If the menu is already active, this event disables keyboard traversal for the menu and returns the menu to mouse traversal mode.

StartDrag():
    Arms the CascadeButton, posts the associated submenu, and enables mouse traversal. If the menu is already active, this event disables keyboard traversal for the menu and returns the menu to mouse traversal mode.

  Additional Behavior

Posting a submenu calls the XmNcascadingCallback callbacks. This widget has the following additional behavior:

<EnterWindow>:
    If keyboard traversal is enabled, does nothing. Otherwise, in a MenuBar that is armed, unposts any MenuPanes associated with another MenuBar entry, arms the CascadeButton, and posts the associated submenu. In other menus, arms the CascadeButton and posts the associated submenu after the delay specified by XmNmappingDelay.

<LeaveWindow>:
    If keyboard traversal is enabled does nothing. Otherwise, in a MenuBar that is armed, disarms the CascadeButton if the submenu associated with the CascadeButton is not currently posted or if there is no submenu associated with the CascadeButton.

    In other menus, if the pointer moves anywhere except into a submenu associated with the CascadeButton, the CascadeButton is disarmed and its submenu is unposted.

  Virtual Bindings

The bindings for virtual keys are vendor specific. For information about bindings for virtual buttons and keys, see VirtualBindings(3).

RELATED

Core(3), XmCascadeButtonHighlight(3), XmCreateCascadeButton(3), XmCreateMenuBar(3), XmCreatePulldownMenu(3), XmCreatePopupMenu(3), XmLabel(3), XmPrimitive(3), and XmRowColumn(3).