## GtkExpander

GtkExpander — A container which can hide its child

## Functions

GtkWidget * | gtk_expander_new ()
GtkWidget * | gtk_expander_new_with_mnemonic ()
void | gtk_expander_set_expanded ()
gboolean | gtk_expander_get_expanded ()
void | gtk_expander_set_spacing ()
gint | gtk_expander_get_spacing ()
void | gtk_expander_set_label ()
const gchar * | gtk_expander_get_label ()
void | gtk_expander_set_use_underline ()
gboolean | gtk_expander_get_use_underline ()
void | gtk_expander_set_use_markup ()
gboolean | gtk_expander_get_use_markup ()
void | gtk_expander_set_label_widget ()
GtkWidget * | gtk_expander_get_label_widget ()
void | gtk_expander_set_label_fill ()
gboolean | gtk_expander_get_label_fill ()
void | gtk_expander_set_resize_toplevel ()
gboolean | gtk_expander_get_resize_toplevel ()

## Properties

gboolean | expanded | Read / Write / Construct
gchar * | label | Read / Write / Construct
gboolean | label-fill | Read / Write / Construct
GtkWidget * | label-widget | Read / Write
gboolean | resize-toplevel | Read / Write
gint | spacing | Read / Write
gboolean | use-markup | Read / Write / Construct
gboolean | use-underline | Read / Write / Construct

## Style Properties

gint | expander-size | Read
gint | expander-spacing | Read

## Signals

void | activate | Action

## Types and Values

struct | GtkExpander
struct | GtkExpanderClass

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── GtkWidget
                ╰── GtkContainer
                    ╰── GtkBin
                        ╰── GtkExpander

## Implemented Interfaces

GtkExpander implements AtkImplementorIface and GtkBuildable.

## Includes

    #include <gtk/gtk.h>

## 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:

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    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
        }
    }

    static void
    create_expander (void)
    {
      GtkWidget *expander = gtk_expander_new_with_mnemonic ("_More Options");
      g_signal_connect (expander, "notify::expanded",
                        G_CALLBACK (expander_callback), NULL);

      // ...
    }

### GtkExpander as GtkBuildable

The GtkExpander implementation of the GtkBuildable interface supports placing a child in the label position by specifying “label” as the “type” attribute of a <child> element. A normal content child can be specified without specifying a <child> type attribute.

An example of a UI definition fragment with GtkExpander:

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    <object class="GtkExpander">
      <child type="label">
        <object class="GtkLabel" id="expander-label"/>
      </child>
      <child>
        <object class="GtkEntry" id="expander-content"/>
      </child>
    </object>

### CSS nodes

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    expander
    ├── title
    │   ├── arrow
    │   ╰── <label widget>
    ╰── <child>

GtkExpander has three CSS nodes, the main node with the name expander, a subnode with name title and node below it with name arrow. The arrow of an expander that is showing its child gets the :checked pseudoclass added to it.

## Functions

### gtk_expander_new ()

    GtkWidget *
    gtk_expander_new (const gchar *label);

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

#### Parameters

label | the text of the label. | [nullable]

#### 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.

#### Parameters

label | the text of the label with an underscore in front of the mnemonic character. | [nullable]

#### 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.

#### Parameters

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()`.

#### Parameters

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);

`gtk_expander_set_spacing` has been deprecated since version 3.20 and should not be used in newly-written code.

Use margins on the child instead.

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

#### Parameters

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);

`gtk_expander_get_spacing` has been deprecated since version 3.20 and should not be used in newly-written code.

Use margins on the child instead.

Gets the value set by `gtk_expander_set_spacing()`.

#### Parameters

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.

#### Parameters

expander | a GtkExpander |
label | a string. | [nullable]

Since: 2.4

### gtk_expander_get_label ()

    const gchar *
    gtk_expander_get_label (GtkExpander *expander);

Fetches the text from a label widget including any embedded underlines indicating mnemonics and Pango markup, 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.

Note that this function behaved differently in versions prior to 2.14 and used to return the label text stripped of embedded underlines indicating mnemonics and Pango markup. This problem can be avoided by fetching the label text directly from the label widget.

#### Parameters

expander | a GtkExpander |

#### Returns

The text of the label widget. This string is owned by the widget and must not be modified or freed.

[nullable]

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.

#### Parameters

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()`.

#### Parameters

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()`.

#### Parameters

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()`.

#### Parameters

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.

#### Parameters

expander | a GtkExpander |
label_widget | the new label widget. | [nullable]

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()`.

#### Parameters

expander | a GtkExpander |

#### Returns

the label widget, or `NULL` if there is none.

[nullable][transfer none]

Since: 2.4

### gtk_expander_set_label_fill ()

    void
    gtk_expander_set_label_fill (GtkExpander *expander,
                                 gboolean label_fill);

Sets whether the label widget should fill all available horizontal space allocated to `expander` .

#### Parameters

expander | a GtkExpander |
label_fill | `TRUE` if the label should should fill all available horizontal space |

Since: 2.22

### gtk_expander_get_label_fill ()

    gboolean
    gtk_expander_get_label_fill (GtkExpander *expander);

Returns whether the label widget will fill all available horizontal space allocated to `expander` .

#### Parameters

expander | a GtkExpander |

#### Returns

`TRUE` if the label widget will fill all available horizontal space

Since: 2.22

### gtk_expander_set_resize_toplevel ()

    void
    gtk_expander_set_resize_toplevel (GtkExpander *expander,
                                      gboolean resize_toplevel);

Sets whether the expander will resize the toplevel widget containing the expander upon resizing and collpasing.

#### Parameters

expander | a GtkExpander |
resize_toplevel | whether to resize the toplevel |

Since: 3.2

### gtk_expander_get_resize_toplevel ()

    gboolean
    gtk_expander_get_resize_toplevel (GtkExpander *expander);

Returns whether the expander will resize the toplevel widget containing the expander upon resizing and collpasing.

#### Parameters

expander | a GtkExpander |

#### Returns

the “resize toplevel” setting.

Since: 3.2

## Types and Values

### struct GtkExpander

    struct GtkExpander;

### struct GtkExpanderClass

    struct GtkExpanderClass {
      GtkBinClass    parent_class;

      /* Key binding signal; to get notification on the expansion
       * state connect to notify:expanded.
       */
      void        (* activate) (GtkExpander *expander);
    };

#### Members

`activate` () | Keybinding signal is emitted when the user hits the Enter key. |

## Property Details

### The `“expanded”` property

      “expanded”                 gboolean

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

Flags: Read / Write / Construct

Default value: FALSE

### The `“label”` property

      “label”                    gchar *

Text of the expander's label.

Flags: Read / Write / Construct

Default value: NULL

### The `“label-fill”` property

      “label-fill”               gboolean

Whether the label widget should fill all available horizontal space.

Flags: Read / Write / Construct

Default value: FALSE

### The `“label-widget”` property

      “label-widget”             GtkWidget *

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

Flags: Read / Write

### The `“resize-toplevel”` property

      “resize-toplevel”          gboolean

When this property is `TRUE`, the expander will resize the toplevel widget containing the expander upon expanding and collapsing.

Flags: Read / Write

Default value: FALSE

Since: 3.2

### The `“spacing”` property

      “spacing”                  gint

Space to put between the label and the child when the expander is expanded.

`GtkExpander:spacing` has been deprecated since version 3.20 and should not be used in newly-written code.

This property is deprecated and ignored. Use margins on the child instead.

Flags: Read / Write

Allowed values: >= 0

Default value: 0

### The `“use-markup”` property

      “use-markup”               gboolean

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

Flags: Read / Write / Construct

Default value: FALSE

### The `“use-underline”` property

      “use-underline”            gboolean

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

Flags: Read / Write / Construct

Default value: FALSE

## Style Property Details

### The `“expander-size”` style property

      “expander-size”            gint

The size of the expander arrow.

`GtkExpander:expander-size` has been deprecated since version 3.20 and should not be used in newly-written code.

Use CSS min-width and min-height instead.

Flags: Read

Allowed values: >= 0

Default value: 10

### The `“expander-spacing”` style property

      “expander-spacing”         gint

Spaing around the expander arrow.

`GtkExpander:expander-spacing` has been deprecated since version 3.20 and should not be used in newly-written code.

Use CSS margins instead, the value of this style property is ignored.

Flags: Read

Allowed values: >= 0

Default value: 2

## Signal Details

### The `“activate”` signal

    void
    user_function (GtkExpander *expander,
                   gpointer     user_data)

Flags: Action