### Function

# Gtk ListBoxUpdateHeaderFunc

#### Declaration

    void
    (* GtkListBoxUpdateHeaderFunc) (
      GtkListBoxRow* row,
      GtkListBoxRow* before,
      gpointer user_data
    )

#### Description [src]

Whenever `row` changes or which row is before `row` changes this is called, which lets you update the header on `row`.

You may remove or set a new one via `gtk_list_box_row_set_header()` or just change the state of the current header widget.

#### Parameters

`row`

  Type: `GtkListBoxRow`

  The row to update.

  The data is owned by the caller of the function.

`before`

  Type: `GtkListBoxRow`

  The row before `row`, or `NULL` if it is first.

  The argument can be `NULL`.
  The data is owned by the caller of the function.

`user_data`

  Type: `gpointer`

  User data.

  The argument can be `NULL`.
  The data is owned by the caller of the function.