Main loop and Events

## Main loop and Events Main loop and Events — Library initialization, main event loop, and events |

## Synopsis

    #include <gtk/gtk.h>

    gchar*              gtk_set_locale                      (void);
    void                gtk_disable_setlocale               (void);
    PangoLanguage*      gtk_get_default_language            (void);
    gboolean            gtk_parse_args                      (int *argc,
                                                             char ***argv);
    void                gtk_init                            (int *argc,
                                                             char ***argv);
    gboolean            gtk_init_check                      (int *argc,
                                                             char ***argv);
    gboolean            gtk_init_with_args                  (int *argc,
                                                             char ***argv,
                                                             char *parameter_string,
                                                             GOptionEntry *entries,
                                                             char *translation_domain,
                                                             GError **error);
    GOptionGroup*       gtk_get_option_group                (gboolean open_default_display);
    void                gtk_exit                            (gint error_code);
    gboolean            gtk_events_pending                  (void);
    void                gtk_main                            (void);
    guint               gtk_main_level                      (void);
    void                gtk_main_quit                       (void);
    gboolean            gtk_main_iteration                  (void);
    gboolean            gtk_main_iteration_do               (gboolean blocking);
    void                gtk_main_do_event                   (GdkEvent *event);
    void                (*GtkModuleInitFunc)                (gint *argc,
                                                             gchar ***argv);
    void                (*GtkModuleDisplayInitFunc)         (GdkDisplay *display);

    gboolean            gtk_true                            (void);
    gboolean            gtk_false                           (void);

    void                gtk_grab_add                        (GtkWidget *widget);
    GtkWidget*          gtk_grab_get_current                (void);
    void                gtk_grab_remove                     (GtkWidget *widget);

    void                gtk_init_add                        (GtkFunction function,
                                                             gpointer data);
    void                gtk_quit_add_destroy                (guint main_level,
                                                             GtkObject *object);
    guint               gtk_quit_add                        (guint main_level,
                                                             GtkFunction function,
                                                             gpointer data);
    guint               gtk_quit_add_full                   (guint main_level,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);
    void                gtk_quit_remove                     (guint quit_handler_id);
    void                gtk_quit_remove_by_data             (gpointer data);

    guint               gtk_timeout_add_full                (guint32 interval,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);
    guint               gtk_timeout_add                     (guint32 interval,
                                                             GtkFunction function,
                                                             gpointer data);
    void                gtk_timeout_remove                  (guint timeout_handler_id);

    guint               gtk_idle_add                        (GtkFunction function,
                                                             gpointer data);
    guint               gtk_idle_add_priority               (gint priority,
                                                             GtkFunction function,
                                                             gpointer data);
    guint               gtk_idle_add_full                   (gint priority,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);
    void                gtk_idle_remove                     (guint idle_handler_id);
    void                gtk_idle_remove_by_data             (gpointer data);

    guint               gtk_input_add_full                  (gint source,
                                                             GdkInputCondition condition,
                                                             GdkInputFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);
    void                gtk_input_remove                    (guint input_handler_id);

    #define             GTK_PRIORITY_REDRAW
    #define             GTK_PRIORITY_RESIZE
    #define             GTK_PRIORITY_HIGH
    #define             GTK_PRIORITY_INTERNAL
    #define             GTK_PRIORITY_DEFAULT
    #define             GTK_PRIORITY_LOW

    guint               gtk_key_snooper_install             (GtkKeySnoopFunc snooper,
                                                             gpointer func_data);
    gint                (*GtkKeySnoopFunc)                  (GtkWidget *grab_widget,
                                                             GdkEventKey *event,
                                                             gpointer func_data);
    void                gtk_key_snooper_remove              (guint snooper_handler_id);

    GdkEvent*           gtk_get_current_event               (void);
    guint32             gtk_get_current_event_time          (void);
    gboolean            gtk_get_current_event_state         (GdkModifierType *state);
    GtkWidget*          gtk_get_event_widget                (GdkEvent *event);
    void                gtk_propagate_event                 (GtkWidget *widget,
                                                             GdkEvent *event);

## Description

Before using GTK+, you need to initialize it; initialization connects to the window system display, and parses some standard command line arguments. The `gtk_init()` function initializes GTK+. `gtk_init()` exits the application if errors occur; to avoid this, use `gtk_init_check()`. `gtk_init_check()` allows you to recover from a failed GTK+ initialization - you might start up your application in text mode instead.

Like all GUI toolkits, GTK+ uses an event-driven programming model. When the user is doing nothing, GTK+ sits in the main loop and waits for input. If the user performs some action - say, a mouse click - then the main loop "wakes up" and delivers an event to GTK+. GTK+ forwards the event to one or more widgets.

When widgets receive an event, they frequently emit one or more signals. Signals notify your program that "something interesting happened" by invoking functions you've connected to the signal with `g_signal_connect()`. Functions connected to a signal are often termed callbacks.

When your callbacks are invoked, you would typically take some action - for example, when an Open button is clicked you might display a GtkFileSelectionDialog. After a callback finishes, GTK+ will return to the main loop and await more user input.

Example 1. Typical `main` function for a GTK+ application

    int
    main (int argc, char **argv)
    {
      /* Initialize i18n support */
      gtk_set_locale ();

      /* Initialize the widget set */
      gtk_init (&argc, &argv);

      /* Create the main window */
      mainwin = gtk_window_new (GTK_WINDOW_TOPLEVEL);

      /* Set up our GUI elements */
      ...

      /* Show the application window */
      gtk_widget_show_all (mainwin);

      /* Enter the main event loop, and wait for user interaction */
      gtk_main ();

      /* The user lost interest */
      return 0;
    }

It's OK to use the GLib main loop directly instead of `gtk_main()`, though it involves slightly more typing. See GMainLoop in the GLib documentation.

## Details

### gtk_set_locale ()

    gchar*              gtk_set_locale                      (void);

Initializes internationalization support for GTK+. `gtk_init()` automatically does this, so there is typically no point in calling this function.

If you are calling this function because you changed the locale after GTK+ is was initialized, then calling this function may help a bit. (Note, however, that changing the locale after GTK+ is initialized may produce inconsistent results and is not really supported.)

In detail - sets the current locale according to the program environment. This is the same as calling the C library function `setlocale (LC_ALL, "")` but also takes care of the locale specific setup of the windowing system used by GDK.

Returns : | a string corresponding to the locale set, typically in the form lang_COUNTRY, where lang is an ISO-639 language code, and COUNTRY is an ISO-3166 country code. On Unix, this form matches the result of the `setlocale()`; it is also used on other machines, such as Windows, where the C library returns a different result. The string is owned by GTK+ and should not be modified or freed.

### gtk_disable_setlocale ()

    void                gtk_disable_setlocale               (void);

Prevents `gtk_init()`, `gtk_init_check()`, `gtk_init_with_args()` and `gtk_parse_args()` from automatically calling `setlocale (LC_ALL, "")`. You would want to use this function if you wanted to set the locale for your program to something other than the user's locale, or if you wanted to set different values for different locale categories.

Most programs should not need to call this function.

### gtk_get_default_language ()

    PangoLanguage*      gtk_get_default_language            (void);

Returns the PangoLanguage for the default language currently in effect. (Note that this can change over the life of an application.) The default language is derived from the current locale. It determines, for example, whether GTK+ uses the right-to-left or left-to-right text direction. See `_gtk_get_lc_ctype()` for notes on behaviour on Windows.

Returns : | the default language as a PangoLanguage, must not be freed

### gtk_parse_args ()

    gboolean            gtk_parse_args                      (int *argc,
                                                             char ***argv);

Parses command line arguments, and initializes global attributes of GTK+, but does not actually open a connection to a display. (See `gdk_display_open()`, `gdk_get_display_arg_name()`)

Any arguments used by GTK+ or GDK are removed from the array and `argc` and `argv` are updated accordingly.

You shouldn't call this function explicitely if you are using `gtk_init()`, or `gtk_init_check()`.

`argc` : | a pointer to the number of command line arguments.
`argv` : | a pointer to the array of command line arguments.
Returns : | `TRUE` if initialization succeeded, otherwise `FALSE`.

### gtk_init ()

    void                gtk_init                            (int *argc,
                                                             char ***argv);

Call this function before using any other GTK+ functions in your GUI applications. It will initialize everything needed to operate the toolkit and parses some standard command line options. `argc` and `argv` are adjusted accordingly so your own code will never see those standard arguments.

Note that there are some alternative ways to initialize GTK+: if you are calling `gtk_parse_args()`, `gtk_init_check()`, `gtk_init_with_args()` or `g_option_context_parse()` with the option group returned by `gtk_get_option_group()`, you don't have to call `gtk_init()`.

### Note

This function will terminate your program if it was unable to initialize the GUI for some reason. If you want your program to fall back to a textual interface you want to call `gtk_init_check()` instead.

### Note

`argc` : | Address of the `argc` parameter of your `main()` function. Changed if any arguments were handled.
`argv` : | Address of the `argv` parameter of `main()`. Any parameters understood by `gtk_init()` are stripped before return.

### gtk_init_check ()

    gboolean            gtk_init_check                      (int *argc,
                                                             char ***argv);

This function does the same work as `gtk_init()` with only a single change: It does not terminate the program if the GUI can't be initialized. Instead it returns `FALSE` on failure.

This way the application can fall back to some other means of communication with the user - for example a curses or command line interface.

`argc` : | Address of the `argc` parameter of your `main()` function. Changed if any arguments were handled.
`argv` : | Address of the `argv` parameter of `main()`. Any parameters understood by `gtk_init()` are stripped before return.
Returns : | `TRUE` if the GUI has been successfully initialized, `FALSE` otherwise.

### gtk_init_with_args ()

    gboolean            gtk_init_with_args                  (int *argc,
                                                             char ***argv,
                                                             char *parameter_string,
                                                             GOptionEntry *entries,
                                                             char *translation_domain,
                                                             GError **error);

This function does the same work as `gtk_init_check()`. Additionally, it allows you to add your own commandline options, and it automatically generates nicely formatted `--help` output. Note that your program will be terminated after writing out the help output.

`argc` : | a pointer to the number of command line arguments.
`argv` : | a pointer to the array of command line arguments.
`parameter_string` : | a string which is displayed in the first line of `--help` output, after ``programname` [OPTION...]`
`entries` : | a `NULL`-terminated array of GOptionEntrys describing the options of your program
`translation_domain` : | a translation domain to use for translating the `--help` output for the options in `entries` with `gettext()`, or `NULL`
`error` : | a return location for errors
Returns : | `TRUE` if the GUI has been successfully initialized, `FALSE` otherwise.

Since 2.6

### gtk_get_option_group ()

    GOptionGroup*       gtk_get_option_group                (gboolean open_default_display);

Returns a GOptionGroup for the commandline arguments recognized by GTK+ and GDK. You should add this group to your GOptionContext with `g_option_context_add_group()`, if you are using `g_option_context_parse()` to parse your commandline arguments.

`open_default_display` : | whether to open the default display when parsing the commandline arguments
Returns : | a GOptionGroup for the commandline arguments recognized by GTK+

Since 2.6

### gtk_exit ()

    void                gtk_exit                            (gint error_code);

### Warning

`gtk_exit` is deprecated and should not be used in newly-written code. Use the standard `exit()` function instead.

Terminates the program and returns the given exit code to the caller. This function will shut down the GUI and free all resources allocated for GTK+.

`error_code` : | Return value to pass to the caller. This is dependent on the target system but at least on Unix systems `0` means success.

### gtk_events_pending ()

    gboolean            gtk_events_pending                  (void);

Checks if any events are pending. This can be used to update the GUI and invoke timeouts etc. while doing some time intensive computation.

Example 2. Updating the GUI during a long computation.

    	/* computation going on */
    ...
            while (gtk_events_pending ())
    	  gtk_main_iteration ();
    ...
    	/* computation continued */

Returns : | `TRUE` if any events are pending, `FALSE` otherwise.

### gtk_main ()

    void                gtk_main                            (void);

Runs the main loop until `gtk_main_quit()` is called. You can nest calls to `gtk_main()`. In that case `gtk_main_quit()` will make the innermost invocation of the main loop return.

### gtk_main_level ()

    guint               gtk_main_level                      (void);

Asks for the current nesting level of the main loop. This can be useful when calling `gtk_quit_add()`.

Returns : | the nesting level of the current invocation of the main loop.

### gtk_main_quit ()

    void                gtk_main_quit                       (void);

Makes the innermost invocation of the main loop return when it regains control.

### gtk_main_iteration ()

    gboolean            gtk_main_iteration                  (void);

Runs a single iteration of the mainloop. If no events are waiting to be processed GTK+ will block until the next event is noticed. If you don't want to block look at `gtk_main_iteration_do()` or check if any events are pending with `gtk_events_pending()` first.

Returns : | `TRUE` if `gtk_main_quit()` has been called for the innermost mainloop.

### gtk_main_iteration_do ()

    gboolean            gtk_main_iteration_do               (gboolean blocking);

Runs a single iteration of the mainloop. If no events are available either return or block dependent on the value of `blocking`.

`blocking` : | `TRUE` if you want GTK+ to block if no events are pending.
Returns : | `TRUE` if `gtk_main_quit()` has been called for the innermost mainloop.

### gtk_main_do_event ()

    void                gtk_main_do_event                   (GdkEvent *event);

Processes a single GDK event. This is public only to allow filtering of events between GDK and GTK+. You will not usually need to call this function directly.

While you should not call this function directly, you might want to know how exactly events are handled. So here is what this function does with the event:

1. Compress enter/leave notify events. If the event passed build an enter/leave pair together with the next event (peeked from GDK) both events are thrown away. This is to avoid a backlog of (de-)highlighting widgets crossed by the pointer.

2. Find the widget which got the event. If the widget can't be determined the event is thrown away unless it belongs to a INCR transaction. In that case it is passed to `gtk_selection_incr_event()`.

3. Then the event is passed on a stack so you can query the currently handled event with `gtk_get_current_event()`.

4. The event is sent to a widget. If a grab is active all events for widgets that are not in the contained in the grab widget are sent to the latter with a few exceptions:

   - Deletion and destruction events are still sent to the event widget for obvious reasons.

   - Events which directly relate to the visual representation of the event widget.

   - Leave events are delivered to the event widget if there was an enter event delivered to it before without the paired leave event.

   - Drag events are not redirected because it is unclear what the semantics of that would be.

   Another point of interest might be that all key events are first passed through the key snooper functions if there are any. Read the description of `gtk_key_snooper_install()` if you need this feature.

5. After finishing the delivery the event is popped from the event stack.

`event` : | An event to process (normally) passed by GDK.

### GtkModuleInitFunc ()

    void                (*GtkModuleInitFunc)                (gint *argc,
                                                             gchar ***argv);

Each GTK+ module must have a function `gtk_module_init()` with this prototype. This function is called after loading the module with the `argc` and `argv` cleaned from any arguments that GTK+ handles itself.

`argc` : | Pointer to the number of arguments remaining after `gtk_init()`.
`argv` : | Points to the argument vector.

### GtkModuleDisplayInitFunc ()

    void                (*GtkModuleDisplayInitFunc)         (GdkDisplay *display);

`display` : |

Since 2.2

### gtk_true ()

    gboolean            gtk_true                            (void);

All this function does it to return `TRUE`. This can be useful for example if you want to inhibit the deletion of a window. Of course you should not do this as the user expects a reaction from clicking the close icon of the window...

Example 3. A persistent window

    ##include <gtk/gtk.h>

    int
    main (int argc, char **argv)
    {
      GtkWidget     *win, *but;

      gtk_init( &argc, &argv );

      win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
      g_signal_connect (win, "delete-event",
                        G_CALLBACK (gtk_true), NULL);
      g_signal_connect (win, "destroy",
    		    G_CALLBACK (gtk_main_quit), NULL);

      but = gtk_button_new_with_label ("Close yourself. I mean it!");
      g_signal_connect_swapped (but, "clicked",
    		  G_CALLBACK (gtk_object_destroy), win);
      gtk_container_add (GTK_CONTAINER (win), but);

      gtk_widget_show_all (win);
      gtk_main ();
      return 0;
    }

Returns : | `TRUE`

### gtk_false ()

    gboolean            gtk_false                           (void);

Analogical to `gtk_true()` this function does nothing but always returns `FALSE`.

Returns : | `FALSE`

### gtk_grab_add ()

    void                gtk_grab_add                        (GtkWidget *widget);

Makes `widget` the current grabbed widget. This means that interaction with other widgets in the same application is blocked and mouse as well as keyboard events are delivered to this widget.

`widget` : | The widget that grabs keyboard and pointer events.

### gtk_grab_get_current ()

    GtkWidget*          gtk_grab_get_current                (void);

Queries the current grab of the default window group.

Returns : | The widget which currently has the grab or `NULL` if no grab is active.

### gtk_grab_remove ()

    void                gtk_grab_remove                     (GtkWidget *widget);

Removes the grab from the given widget. You have to pair calls to `gtk_grab_add()` and `gtk_grab_remove()`.

`widget` : | The widget which gives up the grab.

### gtk_init_add ()

    void                gtk_init_add                        (GtkFunction function,
                                                             gpointer data);

Registers a function to be called when the mainloop is started.

`function` : | Function to invoke when `gtk_main()` is called next.
`data` : | Data to pass to that function.

### gtk_quit_add_destroy ()

    void                gtk_quit_add_destroy                (guint main_level,
                                                             GtkObject *object);

Trigger destruction of `object` in case the mainloop at level `main_level` is quit.

`main_level` : | Level of the mainloop which shall trigger the destruction.
`object` : | Object to be destroyed.

### gtk_quit_add ()

    guint               gtk_quit_add                        (guint main_level,
                                                             GtkFunction function,
                                                             gpointer data);

Registers a function to be called when an instance of the mainloop is left.

`main_level` : | Level at which termination the function shall be called. You can pass 0 here to have the function run at the termination of the current mainloop.
`function` : | The function to call. This should return 0 to be removed from the list of quit handlers. Otherwise the function might be called again.
`data` : | Pointer to pass when calling `function`.
Returns : | A handle for this quit handler (you need this for `gtk_quit_remove()`) or 0 if you passed a `NULL` pointer in `function`.

### gtk_quit_add_full ()

    guint               gtk_quit_add_full                   (guint main_level,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);

Registers a function to be called when an instance of the mainloop is left. In comparison to `gtk_quit_add()` this function adds the possibility to pass a marshaller and a function to be called when the quit handler is freed.

The former can be used to run interpreted code instead of a compiled function while the latter can be used to free the information stored in `data` (while you can do this in `function` as well)... So this function will mostly be used by GTK+ wrappers for languages other than C.

`main_level` : | Level at which termination the function shall be called. You can pass 0 here to have the function run at the termination of the current mainloop.
`function` : | The function to call. This should return 0 to be removed from the list of quit handlers. Otherwise the function might be called again.
`marshal` : | The marshaller to be used. If this is non-`NULL`, `function` is ignored.
`data` : | Pointer to pass when calling `function`.
`destroy` : | Function to call to destruct `data`. Gets `data` as argument.
Returns : | A handle for this quit handler (you need this for `gtk_quit_remove()`) or 0 if you passed a `NULL` pointer in `function`.

### gtk_quit_remove ()

    void                gtk_quit_remove                     (guint quit_handler_id);

Removes a quit handler by its identifier.

`quit_handler_id` : | Identifier for the handler returned when installing it.

### gtk_quit_remove_by_data ()

    void                gtk_quit_remove_by_data             (gpointer data);

Removes a quit handler identified by its `data` field.

`data` : | The pointer passed as `data` to `gtk_quit_add()` or `gtk_quit_add_full()`.

### gtk_timeout_add_full ()

    guint               gtk_timeout_add_full                (guint32 interval,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);

### Warning

`gtk_timeout_add_full` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_timeout_add_full()` instead.

Registers a function to be called periodically. The function will be called repeatedly after `interval` milliseconds until it returns `FALSE` at which point the timeout is destroyed and will not be called again.

`interval` : | The time between calls to the function, in milliseconds (1/1000ths of a second.)
`function` : | The function to call periodically.
`marshal` : | The marshaller to use instead of the function (if non-`NULL`).
`data` : | The data to pass to the function.
`destroy` : | Function to call when the timeout is destroyed or `NULL`.
Returns : | A unique id for the event source.

### gtk_timeout_add ()

    guint               gtk_timeout_add                     (guint32 interval,
                                                             GtkFunction function,
                                                             gpointer data);

### Warning

`gtk_timeout_add` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_timeout_add()` instead.

Registers a function to be called periodically. The function will be called repeatedly after `interval` milliseconds until it returns `FALSE` at which point the timeout is destroyed and will not be called again.

`interval` : | The time between calls to the function, in milliseconds (1/1000ths of a second.)
`function` : | The function to call periodically.
`data` : | The data to pass to the function.
Returns : | A unique id for the event source.

### gtk_timeout_remove ()

    void                gtk_timeout_remove                  (guint timeout_handler_id);

### Warning

`gtk_timeout_remove` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_source_remove()` instead.

Removes the given timeout destroying all information about it.

`timeout_handler_id` : | The identifier returned when installing the timeout.

### gtk_idle_add ()

    guint               gtk_idle_add                        (GtkFunction function,
                                                             gpointer data);

### Warning

`gtk_idle_add` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_idle_add()` instead.

Causes the mainloop to call the given function whenever no events with higher priority are to be processed. The default priority is `GTK_PRIORITY_DEFAULT`, which is rather low.

`function` : | The function to call.
`data` : | The information to pass to the function.
Returns : | a unique handle for this registration.

### gtk_idle_add_priority ()

    guint               gtk_idle_add_priority               (gint priority,
                                                             GtkFunction function,
                                                             gpointer data);

### Warning

`gtk_idle_add_priority` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_idle_add_full()` instead.

Like `gtk_idle_add()` this function allows you to have a function called when the event loop is idle. The difference is that you can give a priority different from `GTK_PRIORITY_DEFAULT` to the idle function.

`priority` : | The priority which should not be above `G_PRIORITY_HIGH_IDLE`. Note that you will interfere with GTK+ if you use a priority above `GTK_PRIORITY_RESIZE`.
`function` : | The function to call.
`data` : | Data to pass to that function.
Returns : | A unique id for the event source.

### gtk_idle_add_full ()

    guint               gtk_idle_add_full                   (gint priority,
                                                             GtkFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);

### Warning

`gtk_idle_add_full` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_idle_add_full()` instead.

Like `gtk_idle_add()` this function allows you to have a function called when the event loop is idle. The difference is that you can give a priority different from `GTK_PRIORITY_DEFAULT` to the idle function.

`priority` : | The priority which should not be above `G_PRIORITY_HIGH_IDLE`. Note that you will interfere with GTK+ if you use a priority above `GTK_PRIORITY_RESIZE`.
`function` : | The function to call.
`marshal` : | The marshaller to use instead of the function (if non-`NULL`).
`data` : | Data to pass to that function.
`destroy` : | Function to call when the timeout is destroyed or `NULL`.
Returns : | A unique id for the event source.

### gtk_idle_remove ()

    void                gtk_idle_remove                     (guint idle_handler_id);

### Warning

`gtk_idle_remove` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_source_remove()` instead.

Removes the idle function with the given id.

`idle_handler_id` : | Identifies the idle function to remove.

### gtk_idle_remove_by_data ()

    void                gtk_idle_remove_by_data             (gpointer data);

### Warning

`gtk_idle_remove_by_data` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_idle_remove_by_data()` instead.

Removes the idle function identified by the user data.

`data` : | remove the idle function which was registered with this user data.

### gtk_input_add_full ()

    guint               gtk_input_add_full                  (gint source,
                                                             GdkInputCondition condition,
                                                             GdkInputFunction function,
                                                             GtkCallbackMarshal marshal,
                                                             gpointer data,
                                                             GtkDestroyNotify destroy);

### Warning

`gtk_input_add_full` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_io_add_watch_full()` instead.

Registers a function to be called when a condition becomes true on a file descriptor.

`source` : | a file descriptor.
`condition` : | the condition.
`function` : | The function to call.
`marshal` : | The marshaller to use instead of the function (if non-`NULL`).
`data` : | callback data passed to `function`.
`destroy` : | callback function to call with `data` when the input handler is removed, or `NULL`.
Returns : | A unique id for the event source; to be used with `gtk_input_remove()`.

### gtk_input_remove ()

    void                gtk_input_remove                    (guint input_handler_id);

### Warning

`gtk_input_remove` has been deprecated since version 2.4 and should not be used in newly-written code. Use `g_source_remove()` instead.

Removes the function with the given id.

`input_handler_id` : | Identifies the function to remove.

### GTK_PRIORITY_REDRAW

    #define GTK_PRIORITY_REDRAW     (G_PRIORITY_HIGH_IDLE + 20)

### Warning

`GTK_PRIORITY_REDRAW` has been deprecated since version 2.4 and should not be used in newly-written code. This macro is deprecated. You should use `GDK_PRIORITY_REDRAW` instead.

Use this priority for redrawing related stuff. It is used internally by GTK+ to do pending redraws. This priority is lower than `GTK_PRIORITY_RESIZE` to avoid redrawing a widget just before resizing (and therefore redrawing it again).

### GTK_PRIORITY_RESIZE

    #define GTK_PRIORITY_RESIZE     (G_PRIORITY_HIGH_IDLE + 10)

Use this priority for resizing related stuff. It is used internally by GTK+ to compute the sizes of widgets. This priority is higher than `GTK_PRIORITY_REDRAW` to avoid resizing a widget which was just redrawn.

### GTK_PRIORITY_HIGH

    #define GTK_PRIORITY_HIGH       G_PRIORITY_HIGH

### Warning

`GTK_PRIORITY_HIGH` has been deprecated since version 2.4 and should not be used in newly-written code. This macro is deprecated. You should use `G_PRIORITY_HIGH` instead.

Use this for high priority timeouts. This priority is never used inside GTK+ so everything running at this priority will be running before anything inside the toolkit.

### GTK_PRIORITY_INTERNAL

    #define GTK_PRIORITY_INTERNAL   GTK_PRIORITY_REDRAW

### Warning

`GTK_PRIORITY_INTERNAL` is deprecated and should not be used in newly-written code.

This priority is for GTK+ internal stuff. Don't use it in your applications.

### GTK_PRIORITY_DEFAULT

    #define GTK_PRIORITY_DEFAULT	G_PRIORITY_DEFAULT_IDLE

### Warning

`GTK_PRIORITY_DEFAULT` has been deprecated since version 2.4 and should not be used in newly-written code. This macro is deprecated. You should use `G_PRIORITY_DEFAULT_IDLE` instead.

Default priority for idle functions.

### GTK_PRIORITY_LOW

    #define GTK_PRIORITY_LOW	G_PRIORITY_LOW

### Warning

`GTK_PRIORITY_LOW` has been deprecated since version 2.4 and should not be used in newly-written code. This macro is deprecated. You should use `G_PRIORITY_LOW` instead.

Priority for very unimportant background tasks.

### gtk_key_snooper_install ()

    guint               gtk_key_snooper_install             (GtkKeySnoopFunc snooper,
                                                             gpointer func_data);

Installs a key snooper function, which will get called on all key events before delivering them normally.

`snooper` : | a GtkKeySnoopFunc.
`func_data` : | data to pass to `snooper`.
Returns : | a unique id for this key snooper for use with `gtk_key_snooper_remove()`.

### GtkKeySnoopFunc ()

    gint                (*GtkKeySnoopFunc)                  (GtkWidget *grab_widget,
                                                             GdkEventKey *event,
                                                             gpointer func_data);

Key snooper functions are called before normal event delivery. They can be used to implement custom key event handling.

`grab_widget` : | the widget to which the event will be delivered.
`event` : | the key event.
`func_data` : | the `func_data` supplied to `gtk_key_snooper_install()`.
Returns : | `TRUE` to stop further processing of `event`, `FALSE` to continue.

### gtk_key_snooper_remove ()

    void                gtk_key_snooper_remove              (guint snooper_handler_id);

Removes the key snooper function with the given id.

`snooper_handler_id` : | Identifies the key snooper to remove.

### gtk_get_current_event ()

    GdkEvent*           gtk_get_current_event               (void);

Obtains a copy of the event currently being processed by GTK+. For example, if you get a "clicked" signal from GtkButton, the current event will be the GdkEventButton that triggered the "clicked" signal. The returned event must be freed with `gdk_event_free()`. If there is no current event, the function returns `NULL`.

Returns : | a copy of the current event, or `NULL` if no current event.

### gtk_get_current_event_time ()

    guint32             gtk_get_current_event_time          (void);

If there is a current event and it has a timestamp, return that timestamp, otherwise return `GDK_CURRENT_TIME`.

Returns : | the timestamp from the current event, or `GDK_CURRENT_TIME`.

### gtk_get_current_event_state ()

    gboolean            gtk_get_current_event_state         (GdkModifierType *state);

If there is a current event and it has a state field, place that state field in `state` and return `TRUE`, otherwise return `FALSE`.

`state` : | a location to store the state of the current event
Returns : | `TRUE` if there was a current event and it had a state field

### gtk_get_event_widget ()

    GtkWidget*          gtk_get_event_widget                (GdkEvent *event);

If `event` is `NULL` or the event was not associated with any widget, returns `NULL`, otherwise returns the widget that received the event originally.

`event` : | a GdkEvent
Returns : | the widget that originally received `event`, or `NULL`

### gtk_propagate_event ()

    void                gtk_propagate_event                 (GtkWidget *widget,
                                                             GdkEvent *event);

Sends an event to a widget, propagating the event to parent widgets if the event remains unhandled. Events received by GTK+ from GDK normally begin in `gtk_main_do_event()`. Depending on the type of event, existence of modal dialogs, grabs, etc., the event may be propagated; if so, this function is used. `gtk_propagate_event()` calls `gtk_widget_event()` on each widget it decides to send the event to. So `gtk_widget_event()` is the lowest-level function; it simply emits the "event" and possibly an event-specific signal on a widget. `gtk_propagate_event()` is a bit higher-level, and `gtk_main_do_event()` is the highest level.

All that said, you most likely don't want to use any of these functions; synthesizing events is rarely needed. Consider asking on the mailing list for better ways to achieve your goals. For example, use `gdk_window_invalidate_rect()` or `gtk_widget_queue_draw()` instead of making up expose events.

`widget` : | a GtkWidget
`event` : | an event

## See Also

See the GLib manual, especially GMainLoop and signal-related functions such as `g_signal_connect()`.