XmDisplay

The Display widget class

Format

#include <Xm/Display.h>

DESCRIPTION

The XmDisplay object is used by the Motif widgets to store information that is specific to a display. It also allows the toolkit to access certain information on widget hierarchies that would otherwise be unavailable. Each client has one XmDisplay object for each display it accesses.

An XmDisplay object is automatically created when the application creates the first shell on a display (usually accomplished by a call to XtAppInitialize or XtAppCreateShell). It is not necessary to create an XmDisplay object by any other means. An application can use the function XmGetXmDisplay to obtain the widget ID of the XmDisplay object for a given display.

An application cannot supply initial values for XmDisplay resources as arguments to a call to any function that creates widgets. The application or user can supply initial values in a resource file. After creating the first shell on the display, the application can use XmGetXmDisplay to obtain the widget ID of the XmDisplay object and then call XtSetValues to set the XmDisplay resources.

XmDisplay resources specify the drag protocol style for a client participating in drag and drop transactions. The two basic protocol types are preregister and dynamic. When a preregister protocol is used, the toolkit handles any communication between the initiator and receiver clients and displays the appropriate drag-over and drag-under visual effects. A client registers its drop sites in advance and this information is stored in a property for each top-level window. When the drag pointer enters a top-level window, the drop site information is read by the initiator. A dynamic protocol allows the source and destination clients to dynamically communicate drag and drop state information between each other, and to update their respective visuals accordingly. The toolkit provides drop site information as the pointer passes over any given drop site. In this mode, a receiver can supply a procedure to generate its own drag-under effects.

Classes

Display inherits behavior and resources from Core, Composite, Shell, WMShell, VendorShell, TopLevelShell, and ApplicationShell classes.

The class pointer is xmDisplayClass.

The class name is XmDisplay.

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).

*defaultVirtualBindings: \
        osfBackSpace:       <Key>BackSpace       \n\
        osfInsert:       <Key>InsertChar      \n\
        osfDelete:       <Key>DeleteChar      \n\
        ...
        osfLeft:       <Key>left,
Ctrl<Key>H

Inherited Resources

All of the superclass resources inherited by XmDisplay are designated N/A (not applicable).

Callback Information

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

typedef struct
{
        int 
reason;
        XEvent  *
event;
        Widget 
timeStamp;
        Boolean 
doit;
}XmDragStartCallbackStruct;

typedef struct
{
        int 
reason;
        XEvent *
event;
        XmRendition 
rendition;
        char *
font_name;
        XmRenderTable 
render_table;
        XmStringTag tag;
}XmDisplayCallbackStruct;