## GtkExpander GtkExpander — A container which can hide its child |

## Synopsis

    #include <gtk/gtk.h>

                GtkExpander;
    GtkWidget*  gtk_expander_new                (const gchar *label);
    GtkWidget*  gtk_expander_new_with_mnemonic  (const gchar *label);
    void        gtk_expander_set_expanded       (GtkExpander *expander,
                                                 gboolean expanded);
    gboolean    gtk_expander_get_expanded       (GtkExpander *expander);
    void        gtk_expander_set_spacing        (GtkExpander *expander,
                                                 gint spacing);
    gint        gtk_expander_get_spacing        (GtkExpander *expander);
    void        gtk_expander_set_label          (GtkExpander *expander,
                                                 const gchar *label);
    const gchar* gtk_expander_get_label         (GtkExpander *expander);
    void        gtk_expander_set_use_underline  (GtkExpander *expander,
                                                 gboolean use_underline);
    gboolean    gtk_expander_get_use_underline  (GtkExpander *expander);
    void        gtk_expander_set_use_markup     (GtkExpander *expander,
                                                 gboolean use_markup);
    gboolean    gtk_expander_get_use_markup     (GtkExpander *expander);
    void        gtk_expander_set_label_widget   (GtkExpander *expander,
                                                 GtkWidget *label_widget);
    GtkWidget*  gtk_expander_get_label_widget   (GtkExpander *expander);

## Object Hierarchy

      GObject
       +----GtkObject
             +----GtkWidget
                   +----GtkContainer
                         +----GtkBin
                               +----GtkExpander

## Implemented Interfaces

GtkExpander implements AtkImplementorIface.

## Properties

      "expanded"             gboolean              : Read / Write / Construct
      "label"                gchararray            : Read / Write / Construct
      "label-widget"         GtkWidget             : Read / Write
      "spacing"              gint                  : Read / Write
      "use-markup"           gboolean              : Read / Write / Construct
      "use-underline"        gboolean              : Read / Write / Construct

## Style Properties

      "expander-size"        gint                  : Read
      "expander-spacing"     gint                  : Read

## Signal Prototypes

    "activate"  void        user_function      (GtkExpander *expander,
                                                gpointer user_data);

## Description

A GtkExpander allows the user to hide or show its child by clicking on an expander triangle similar to the triangles used in a GtkTreeView.

Normally you use an expander as you would use any other descendant of GtkBin; you create the child widget and use `gtk_container_add()` to add it to the expander. When the expander is toggled, it will take care of showing and hiding the child automatically.

## Special Usage

There are situations in which you may prefer to show and hide the expanded widget yourself, such as when you want to actually create the widget at expansion time. In this case, create a GtkExpander but do not add a child to it. The expander widget has an `expanded` property which can be used to monitor its expansion state. You should watch this property with a signal connection as follows:

    expander = gtk_expander_new_with_mnemonic ("_More Options");
    g_signal_connect (expander, "notify::expanded",
                      G_CALLBACK (expander_callback), NULL);

    ...

    static void
    expander_callback (GObject    *object,
                       GParamSpec *param_spec,
                       gpointer    user_data)
    {
      GtkExpander *expander;

      expander = GTK_EXPANDER (object);

      if (gtk_expander_get_expanded (expander))
        {
          /* Show or create widgets */
        }
      else
        {
          /* Hide or destroy widgets */
        }
    }

## Details

### GtkExpander

    typedef struct _GtkExpander GtkExpander;

### gtk_expander_new ()

    GtkWidget*  gtk_expander_new                (const gchar *label);

Creates a new expander using `label` as the text of the label.

`label` : | the text of the label
Returns : | a new GtkExpander widget.

Since 2.4

### gtk_expander_new_with_mnemonic ()

    GtkWidget*  gtk_expander_new_with_mnemonic  (const gchar *label);

Creates a new expander using `label` as the text of the label. If characters in `label` are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use '__' (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. Pressing Alt and that key activates the button.

`label` : | the text of the label with an underscore in front of the mnemonic character
Returns : | a new GtkExpander widget.

Since 2.4

### gtk_expander_set_expanded ()

    void        gtk_expander_set_expanded       (GtkExpander *expander,
                                                 gboolean expanded);

Sets the state of the expander. Set to `TRUE`, if you want the child widget to be revealed, and `FALSE` if you want the child widget to be hidden.

`expander` : | a GtkExpander
`expanded` : | whether the child widget is revealed

Since 2.4

### gtk_expander_get_expanded ()

    gboolean    gtk_expander_get_expanded       (GtkExpander *expander);

Queries a GtkExpander and returns its current state. Returns `TRUE` if the child widget is revealed.

See `gtk_expander_set_expanded()`.

`expander` : | a GtkExpander
Returns : | the current state of the expander.

Since 2.4

### gtk_expander_set_spacing ()

    void        gtk_expander_set_spacing        (GtkExpander *expander,
                                                 gint spacing);

Sets the spacing field of `expander`, which is the number of pixels to place between expander and the child.

`expander` : | a GtkExpander
`spacing` : | distance between the expander and child in pixels.

Since 2.4

### gtk_expander_get_spacing ()

    gint        gtk_expander_get_spacing        (GtkExpander *expander);

Gets the value set by `gtk_expander_set_spacing()`.

`expander` : | a GtkExpander
Returns : | spacing between the expander and child.

Since 2.4

### gtk_expander_set_label ()

    void        gtk_expander_set_label          (GtkExpander *expander,
                                                 const gchar *label);

Sets the text of the label of the expander to `label`.

This will also clear any previously set labels.

`expander` : | a GtkExpander
`label` : | a string

Since 2.4

### gtk_expander_get_label ()

    const gchar* gtk_expander_get_label         (GtkExpander *expander);

Fetches the text from the label of the expander, as set by `gtk_expander_set_label()`. If the label text has not been set the return value will be `NULL`. This will be the case if you create an empty button with `gtk_button_new()` to use as a container.

`expander` : | a GtkExpander
Returns : | The text of the label widget. This string is owned by the widget and must not be modified or freed.

Since 2.4

### gtk_expander_set_use_underline ()

    void        gtk_expander_set_use_underline  (GtkExpander *expander,
                                                 gboolean use_underline);

If true, an underline in the text of the expander label indicates the next character should be used for the mnemonic accelerator key.

`expander` : | a GtkExpander
`use_underline` : | `TRUE` if underlines in the text indicate mnemonics

Since 2.4

### gtk_expander_get_use_underline ()

    gboolean    gtk_expander_get_use_underline  (GtkExpander *expander);

Returns whether an embedded underline in the expander label indicates a mnemonic. See `gtk_expander_set_use_underline()`.

`expander` : | a GtkExpander
Returns : | `TRUE` if an embedded underline in the expander label indicates the mnemonic accelerator keys.

Since 2.4

### gtk_expander_set_use_markup ()

    void        gtk_expander_set_use_markup     (GtkExpander *expander,
                                                 gboolean use_markup);

Sets whether the text of the label contains markup in Pango's text markup language. See `gtk_label_set_markup()`.

`expander` : | a GtkExpander
`use_markup` : | `TRUE` if the label's text should be parsed for markup

Since 2.4

### gtk_expander_get_use_markup ()

    gboolean    gtk_expander_get_use_markup     (GtkExpander *expander);

Returns whether the label's text is interpreted as marked up with the Pango text markup language. See `gtk_expander_set_use_markup()`.

`expander` : | a GtkExpander
Returns : | `TRUE` if the label's text will be parsed for markup

Since 2.4

### gtk_expander_set_label_widget ()

    void        gtk_expander_set_label_widget   (GtkExpander *expander,
                                                 GtkWidget *label_widget);

Set the label widget for the expander. This is the widget that will appear embedded alongside the expander arrow.

`expander` : | a GtkExpander
`label_widget` : | the new label widget

Since 2.4

### gtk_expander_get_label_widget ()

    GtkWidget*  gtk_expander_get_label_widget   (GtkExpander *expander);

Retrieves the label widget for the frame. See `gtk_expander_set_label_widget()`.

`expander` : | a GtkExpander
Returns : | the label widget, or `NULL` if there is none.

Since 2.4

## Properties

### The "`expanded`" property

      "expanded"             gboolean              : Read / Write / Construct

Whether the expander has been opened to reveal the child widget.

Default value: FALSE

### The "`label`" property

      "label"                gchararray            : Read / Write / Construct

Text of the expander's label.

Default value: NULL

### The "`label-widget`" property

      "label-widget"         GtkWidget             : Read / Write

A widget to display in place of the usual expander label.

### The "`spacing`" property

      "spacing"              gint                  : Read / Write

Space to put between the label and the child.

Allowed values: >= 0

Default value: 0

### The "`use-markup`" property

      "use-markup"           gboolean              : Read / Write / Construct

The text of the label includes XML markup. See pango_parse_markup().

Default value: FALSE

### The "`use-underline`" property

      "use-underline"        gboolean              : Read / Write / Construct

If set, an underline in the text indicates the next character should be used for the mnemonic accelerator key.

Default value: FALSE

## Style Properties

### The "`expander-size`" style property

      "expander-size"        gint                  : Read

Size of the expander arrow.

Allowed values: >= 0

Default value: 10

### The "`expander-spacing`" style property

      "expander-spacing"     gint                  : Read

Spacing around expander arrow.

Allowed values: >= 0

Default value: 2

## Signals

### The "activate" signal

    void        user_function                  (GtkExpander *expander,
                                                gpointer user_data);

`expander` : | the object which received the signal.
`user_data` : | user data set when the signal handler was connected.