docs(msgbox): update to reflect latest (#6603)

docs/widgets/msgbox.rst

@@ -7,12 +7,14 @@ Message box (lv_msgbox)
 Overview
 ********
 
-The Message boxes act as pop-ups. They are built from a background
-container, a title, an optional close button, a text and optional
-buttons.
+Message boxes act as pop-ups. They are built from a content area
+with a helper to add text, an optional header (which can have
+a title, a close button, and other buttons), and an optional footer
+with buttons.
 
-The text will be broken into multiple lines automatically and the height
-will be set automatically to include the text and the buttons.
+The text will be broken into multiple lines and the height
+will be set automatically. If the height
+is set manually, the content will become scrollable.
 
 The message box can be modal (blocking clicks on the rest of the screen)
 or not modal.
@@ -25,10 +27,9 @@ Parts and Styles
 The message box is built from other widgets, so you can check these
 widgets' documentation for details.
 
-- Background: :ref:`lv_obj`
-- Close button: :ref:`lv_button`
-- Title and text: :ref:`lv_label`
-- Buttons: :ref:`lv_buttonmatrix`
+- Content, header, and footer: :ref:`lv_obj`
+- Buttons: :ref:`lv_button`
+- Title and content text: :ref:`lv_label`
 
 .. _lv_msgbox_usage:
 
@@ -38,15 +39,8 @@ Usage
 Create a message box
 --------------------
 
-:cpp:expr:`lv_msgbox_create(parent, title, txt, btn_txts[], add_close_btn)`
-creates a message box.
-
-If ``parent`` is ``NULL`` the message box will be modal. ``title`` and
-``txt`` are strings for the title and the text. ``btn_txts[]`` is an
-array with the buttons' text.
-
-E.g. :cpp:expr:`const char * btn_txts[] = {"Ok", "Cancel", NULL}`. 
-``add_close_btn`` can be ``true`` or ``false`` to add/don't add a close button.
+:cpp:expr:`lv_msgbox_create(parent)` creates a message box.
+If ``parent`` is ``NULL`` the message box will be modal.
 
 Get the parts
 -------------
@@ -56,29 +50,37 @@ following functions:
 
 .. code:: c
 
-   lv_obj_t * lv_msgbox_get_title(lv_obj_t * mbox);
-   lv_obj_t * lv_msgbox_get_close_btn(lv_obj_t * mbox);
-   lv_obj_t * lv_msgbox_get_text(lv_obj_t * mbox);
-   lv_obj_t * lv_msgbox_get_btns(lv_obj_t * mbox);
+   lv_obj_t * lv_msgbox_get_content(lv_obj_t * obj);
+   lv_obj_t * lv_msgbox_get_title(lv_obj_t * obj);
+   lv_obj_t * lv_msgbox_get_header(lv_obj_t * obj);
+   lv_obj_t * lv_msgbox_get_footer(lv_obj_t * obj);
+
+Functions that add something to the message box return the newly added object:
+
+.. code:: c
+
+   lv_obj_t * lv_msgbox_add_text(lv_obj_t * obj, const char * text);
+   lv_obj_t * lv_msgbox_add_title(lv_obj_t * obj, const char * title);
+   lv_obj_t * lv_msgbox_add_close_button(lv_obj_t * obj);
+   lv_obj_t * lv_msgbox_add_header_button(lv_obj_t * obj, const void * icon);
+   lv_obj_t * lv_msgbox_add_footer_button(lv_obj_t * obj, const char * text);
+
 
 Close the message box
 ---------------------
 
 :cpp:expr:`lv_msgbox_close(msgbox)` closes (deletes) the message box.
 
+:cpp:expr:`lv_msgbox_close_async(msgbox)` closes (deletes) the message box
+asynchronously. This is useful if you want the message box to close the on
+the next call to ``lv_timer_handler`` instead of immediately.
+
 .. _lv_msgbox_events:
 
 Events
 ******
 
--  :cpp:enumerator:`LV_EVENT_VALUE_CHANGED` is sent by the buttons if one of them is
-   clicked. :cpp:enumerator:`LV_OBJ_FLAG_EVENT_BUBBLE` is enabled on the buttons so
-   you can add events to the message box itself. In the event handler,
-   :cpp:expr:`lv_event_get_target(e)` will return the button matrix and
-   :cpp:expr:`lv_event_get_current_target(e)` will return the message box.
-   :cpp:expr:`lv_msgbox_get_active_button(msgbox)` and
-   :cpp:expr:`lv_msgbox_get_active_button_text(msgbox)` can be used to get the
-   index and text of the clicked button.
+No special events are sent by this widget.
 
 Learn more about :ref:`events`.
 
@@ -87,8 +89,7 @@ Learn more about :ref:`events`.
 Keys
 ****
 
-Keys have effect on the close button and button matrix. You can add them
-manually to a group if required.
+No *Keys* are processed by the object type.
 
 Learn more about :ref:`indev_keys`.