gdk_spawn API proposal

[Mark McLoughlin <mark skynet ie>]

Hi,
	I'd forgotten about this one. The bug is:

http://bugzilla.gnome.org/show_bug.cgi?id=95897

	Its not on gtk.org/plan/2.4/ but its still on the 2.4 milestone, so I
thought I'd put the API out for review.

=======

	Multiscreen applications which launch other applications as a result of
user interaction need to be able to influence the screen on which the
launcher application will display.

	This can be done by modifying the DISPLAY environment variable of the
child process so that the default screen of the launcher application is
the same screen as which the user interaction resulting in the launch
took place.

	This strikes me as a fairly common operation for multiscreen
applications and, as such, it would useful to provide some form of API
help. 

	The API below is implemented in libegg[1]. Originally, a gnome-exec
form of the API was used for the multiscreen support in gnome-panel,
gnome-desktop, gnome-session, nautilus and gnome-applets in GNOME 2.2.

	There are some issues that definetly need discussion, though:

	1) Is this actually a common enough operation to warrant toolkit level
support?

	2) Does application launching support belong in the toolkit? If not is
there any better place for us to provide some form of API to make this
operation easier?

	A proposed API is below.

Good Luck,
Mark.

[1] - libegg/screen-exec/egg-status-icon.[ch]



/* Return a copy of the current environment with DISPLAY modified
 * (or added) to the screen/display indicated by @screen.
 */
gchar **gdk_make_spawn_environment_for_screen (GdkScreen  *screen,
					       gchar     **envp);

/* Wrappers of g_spawn_* but with an extra @screen arg that allows
 * one to spawn a process with DISPLAY set as appropriate so that
 * @screen would be the default screen/display of the spawned process.
 */
gboolean gdk_spawn_async_on_screen (const gchar           *working_directory,
				    gchar                **argv,
				    gchar                **envp,
				    GSpawnFlags            flags,
				    GSpawnChildSetupFunc   child_setup,
				    gpointer               user_data,
				    GdkScreen             *screen,
				    gint                  *child_pid,
				    GError               **error);

gboolean gdk_spawn_async_with_pipes_on_screen (const gchar          *working_directory,
					       gchar               **argv,
					       gchar               **envp,
					       GSpawnFlags           flags,
					       GSpawnChildSetupFunc  child_setup,
					       gpointer              user_data,
					       GdkScreen            *screen,
					       gint                 *child_pid,
					       gint                 *standard_input,
					       gint                 *standard_output,
					       gint                 *standard_error,
					       GError              **error);

gboolean gdk_spawn_sync_on_screen (const gchar          *working_directory,
				   gchar               **argv,
				   gchar               **envp,
				   GSpawnFlags           flags,
				   GSpawnChildSetupFunc  child_setup,
				   gpointer              user_data,
				   GdkScreen            *screen,
				   gchar               **standard_output,
				   gchar               **standard_error,
				   gint                 *exit_status,
				   GError              **error);

gboolean gdk_spawn_command_line_sync_on_screen  (const gchar          *command_line,
						 GdkScreen            *screen,
						 gchar               **standard_output,
						 gchar               **standard_error,
						 gint                 *exit_status,
						 GError              **error);
gboolean gdk_spawn_command_line_async_on_screen (const gchar          *command_line,
						 GdkScreen            *screen,
						 GError              **error);