XmCascadeButtonGadget

library call

`XmCascadeButtonGadget`

The CascadeButtonGadget widget class

    &npzwc;#include <Xm/CascadeBG.h>

## DESCRIPTION

CascadeButtonGadget links two menu panes, a MenuBar to a menu pane, or an OptionMenu 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`, `XmMENU_PULLDOWN`, or `XmMENU_OPTION`.

It is the only gadget that can have a Pulldown menu pane attached to it as a submenu. The submenu is displayed when this gadget is activated within a PopupMenu, a PulldownMenu, or an OptionMenu. 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 an OptionMenu. The positioning of the PulldownMenu with respect to the CascadeButton depends on the `XmNlayoutDirection` resource of the MenuShell.

The default behavior associated with a CascadeButtonGadget depends on the type of menu system in which it resides. By default, `BSelect` controls the behavior of the CascadeButtonGadget. In addition, `BMenu` controls the behavior of the CascadeButtonGadget 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 CascadeButtonGadget'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 CascadeButtonGadget within a Pulldown or Popup menu pane is armed as the result of the user moving the mouse pointer into the gadget, it does not immediately display its submenu. Instead, it waits a short time to see if the arming was temporary (that is, the user was simply passing through the gadget), or the user really wanted the submenu posted. This delay is configurable using `XmNmappingDelay`.

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

If a CascadeButtonGadget 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 LabelGadget's default, which is 2.

CascadeButtonGadget uses the XmQTmenuSystem and XmQTspecifyRenderTable traits.

### Classes

CascadeButtonGadget inherits behavior, resources, and traits from the `Object`, `RectObj`, `XmGadget`, and `XmLabelGadget` classes.

The class pointer is xmCascadeButtonGadgetClass.

The class name is `XmCascadeButtonGadget`.

### 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).

`XmCascadeButtonGadget`
`Name` | `Class` | `Type` | `Default` | `Access`
XmNactivateCallback | XmCCallback | XtCallbackList | NULL | C
XmNcascadePixmap | XmCPixmap | Pixmap | dynamic | CSG
XmNcascadingCallback | XmCCallback | XtCallbackList | NULL | C
XmNmappingDelay | XmCMappingDelay | int | 180 ms | CSG
XmNsubMenuId | XmCMenuWidget | Widget | NULL | CSG

`XmNactivateCallback`

- Specifies the list of callbacks that is called when the user activates the CascadeButtonGadget, 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 gadget 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 gadget when a CascadeButtonGadget is used within a Popup or Pulldown menu pane and a submenu is attached. The LabelGadget class resources `XmNmarginBottom`, `XmNmarginLeft`, `XmNmarginRight`, and `XmNmarginTop` may be modified to ensure that room is left for the cascade pixmap. The default cascade pixmap in menus other than option menus is an arrow pointing to the side of the menu where the submenu will appear. The default for the CascadeButtonGadget in an option menu is `XmUNSPECIFIED_PIXMAP`.

  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 the CascadeButtonGadget. The reason sent by the callback is `XmCR_CASCADING`.

`XmNmappingDelay`

- Specifies the amount of time, in milliseconds, between when a CascadeButtonGadget becomes armed and when it maps its submenu. This delay is used only when the gadget 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 CascadeButtonGadget. The specified menu pane is displayed when the CascadeButtonGadget becomes armed. The menu pane must have been created with the appropriate parentage depending on the type of menu used. See &cdeman.XmCreatePulldownMenu;, &cdeman.XmCreatePopupMenu;, and &cdeman.XmCreateOptionMenu; for more information on the menu systems.

### Inherited Resources

CascadeButtonGadget 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.

`XmLabelGadget Resource Set`
`Name` | `Class` | `Type` | `Default` | `Access`
XmNaccelerator | XmCAccelerator | String | NULL | N/A
XmNacceleratorText | XmCAcceleratorText | XmString | NULL | N/A
XmNalignment | XmCAlignment | unsigned char | dynamic | CSG
XmNfontList | XmCFontList | XmFontList | dynamic | CSG
XmNlabelInsensitivePixmap | XmCLabelInsensitivePixmap | Pixmap | XmUNSPECIFIED_PIXMAP | CSG
XmNlabelPixmap | XmCLabelPixmap | Pixmap | XmUNSPECIFIED_PIXMAP | CSG
XmNlabelString | XmCXmString | XmString | dynamic | CSG
XmNlabelType | XmCLabelType | unsigned char | XmSTRING | CSG
XmNmarginBottom | XmCMarginBottom | Dimension | dynamic | CSG
XmNmarginHeight | XmCMarginHeight | Dimension | 2 | CSG
XmNmarginLeft | XmCMarginLeft | Dimension | 0 | CSG
XmNmarginRight | XmCMarginRight | Dimension | dynamic | CSG
XmNmarginTop | XmCMarginTop | Dimension | dynamic | CSG
XmNmarginWidth | XmCMarginWidth | Dimension | dynamic | CSG
XmNmnemonic | XmCMnemonic | KeySym | NULL | CSG
XmNmnemonicCharSet | XmCMnemonicCharSet | String | dynamic | CSG
XmNrecomputeSize | XmCRecomputeSize | Boolean | True | CSG
XmNrenderTable | XmCRenderTable | XmRenderTable | dynamic | CSG
XmNstringDirection | XmCStringDirection | XmStringDirection | dynamic | CSG

`XmGadget Resource Set`
`Name` | `Class` | `Type` | `Default` | `Access`
XmNbackground | XmCBackground | Pixel | dynamic | CSG
XmNbackgroundPixmap | XmCPixmap | Pixmap | XmUNSPECIFIED_PIXMAP | CSG
XmNbottomShadowColor | XmCBottomShadowColor | Pixel | dynamic | CSG
XmNbottomShadowPixmap | XmCBottomShadowPixmap | Pixmap | dynamic | CSG
XmNhelpCallback | XmCCallback | XtCallbackList | NULL | C
XmNforeground | XmCForeground | Pixel | dynamic | CSG
XmNhighlightColor | XmCHighlightColor | Pixel | dynamic | CSG
XmNhighlightOnEnter | XmCHighlightOnEnter | Boolean | False | CSG
XmNhighlightPixmap | XmCHighlightPixmap | Pixmap | dynamic | CSG
XmNhighlightThickness | XmCHighlightThickness | Dimension | 0 | CSG
XmNlayoutDirection | XmNCLayoutDirection | XmDirection | dynamic | CG
XmNnavigationType | XmCNavigationType | XmNavigationType | XmNONE | CSG
XmNshadowThickness | XmCShadowThickness | Dimension | 2 | CSG
XmNtopShadowColor | XmCTopShadowColor | Pixel | dynamic | CSG
XmNtopShadowPixmap | XmCTopShadowPixmap | Pixmap | dynamic | CSG
XmNtraversalOn | XmCTraversalOn | Boolean | True | CSG
XmNunitType | XmCUnitType | unsigned char | dynamic | CSG
XmNuserData | XmCUserData | XtPointer | NULL | CSG

`RectObj Resource Set`
`Name` | `Class` | `Type` | `Default` | `Access`
XmNancestorSensitive | XmCSensitive | Boolean | dynamic | G
XmNborderWidth | XmCBorderWidth | Dimension | 0 | N/A
XmNheight | XmCHeight | Dimension | dynamic | CSG
XmNsensitive | XmCSensitive | Boolean | True | CSG
XmNwidth | XmCWidth | Dimension | dynamic | CSG
XmNx | XmCPosition | Position | 0 | CSG
XmNy | XmCPosition | Position | 0 | CSG

`Object Resource Set`
`Name` | `Class` | `Type` | `Default` | `Access`
XmNdestroyCallback | XmCCallback | XtCallbackList | NULL | C

### 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 by an XEvent

### Behavior

`XmCascadeButtonGadget` includes behavior from `XmGadget`. `XmCascadeButton` includes the menu traversal behavior from `XmLabel`. Additional `XmCascadeButtonGadget` behavior is described in the following list (in a Popup menu system, Btn3 also performs the Btn1 actions).

Btn1Down:

- Unposts any menus posted by the parent menu. Arms the CascadeButtonGadget, posts the associated submenu, enables mouse traversal, and, in a MenuBar, arms the MenuBar. If the menu is already active, this event disables keyboard traversal for the menu and returns the menu to mouse traversal mode.

Btn1Up:

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

Key osfActivate:

- Calls the callbacks in `XmNcascadingCallback`, and posts the submenu attached to the CascadeButtonGadget if keyboard traversal is enabled in the menu. If the CascadeButtonGadget does not have a submenu attached, this action calls the callbacks in `XmNactivateCallback`, activates the CascadeButtonGadget, and unposts all posted menus in the cascade. This action applies only to gadgets in MenuBars, PulldownMenus, and PopupMenus. For a CascadeButtonGadget in an OptionMenu, if the parent is a manager, this action passes the event to the parent.

Key osfSelect:

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

Key osfHelp:

- 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.

Key osfCancel:

- In a MenuBar, disarms the CascadeButtonGadget 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. For a CascadeButtonGadget in an OptionMenu, if the parent is a manager, this action passes the event to the parent.

  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 restores keyboard focus to the widget from which the menu was posted.

Enter:

- If keyboard traversal is enabled does nothing. Otherwise, in a MenuBar, unposts any MenuPanes associated with another MenuBar entry, arms the CascadeButtonGadget, and posts the associated submenu. In other menus, arms the CascadeButtonGadget and posts the associated submenu after the delay specified by `XmNmappingDelay`.

Leave:

- If keyboard traversal is enabled does nothing. Otherwise, in a MenuBar, disarms the CascadeButtonGadget if the submenu associated with the CascadeButtonGadget is not currently posted or if there is no submenu associated with the CascadeButtonGadget.

  In other menus, if the pointer moves anywhere except into a submenu associated with the CascadeButtonGadget, the CascadeButtonGadget 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 &cdeman.VirtualBindings;.

## RELATED

&cdeman.Object;, &cdeman.RectObj;, &cdeman.XmCascadeButtonHighlight;, &cdeman.XmCreateCascadeButtonGadget;, &cdeman.XmCreatePulldownMenu;, &cdeman.XmCreatePopupMenu;, &cdeman.XmCreateOptionMenu;, &cdeman.XmGadget;, &cdeman.XmLabelGadget;, and &cdeman.XmRowColumn;.