Volume 6A: Motif Programming Manual

{

Widget toplevel = (Widget) client_data;

extern char *SaveStateAndReturnFileName(); /* hypothetical function */

char *filename = SaveStateAndReturnFileName ();

puts("save_state()");

save_argv = (char **) XtRealloc (save_argv,

(save_argc+2) * sizeof (char *));

save_argv[save_argc++] = "−restart";

save_argv[save_argc++] = filename;

XSetCommand (XtDisplay (toplevel), XtWindow (toplevel),

save_argv, save_argc); /* notice the order of these args! */

}

This program registers the WM_SAVE_YOURSELF protocol using XmAddWMProtocols() before it specifies the

callback routine. If the session manager sends a WM_SAVE_YOURSELF message to this program then the

save_state() function is called, which causes the program to save its internal state using the function

SaveStateAndReturnFileName(). This is a hypothetical function that you would write yourself to save the

state of the program and return the filename that contains the state information. The callback routine also adds the

−restart flag and the new filename to the saved argv from the beginning of the program. The function

XSetCommand() is used to set the WM_COMMAND property on the window associated with the top−level shell,

which fulfills the program's obligation to the session manager.

For more information about session managers and the save−yourself communication protocol, see Volume Zero, X

Protocol Reference Manual. For more details on XSetCommand() and other Xlib−based functions that set and get

window manager properties on top−level windows, ...