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<glossary id="glossary">
<title>Glossary</title>
<glossentry id="allocation">
<glossterm>allocation</glossterm>
<glossdef>
<para>
The final size of a <glossterm
linkend="widget">widget</glossterm> within its <glossterm
linkend="parent">parent</glossterm>. For example, a widget
may request a minimum size of 20×20 pixels, but its
parent may decide to allocate 50×20 pixels for it
instead.
</para>
<glossseealso>
<glossterm linkend="requisition">requisition</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="bin">
<glossterm>bin</glossterm>
<glossdef>
<para>
A <glossterm linkend="container">container</glossterm> that
can hold at most one child widget. The base class for bins is
#GtkBin.
</para>
<glossseealso>
<glossterm linkend="container">container</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="child">
<glossterm>child</glossterm>
<glossdef>
<para>
A <glossterm linkend="container">container's</glossterm> child
is a <glossterm linkend="widget">widget</glossterm> contained
inside it.
</para>
</glossdef>
</glossentry>
<glossentry id="column">
<glossterm>column</glossterm>
<glossdef>
<para>
GTK+ contains several widgets which display data in columns,
e.g. the #GtkTreeView.
These <glossterm linkend="view-column">view columns</glossterm> in
the tree view are represented by #GtkTreeViewColumn
objects inside GTK+. They should not be confused with
<glossterm linkend="model-column">model columns</glossterm> which
are used to organize the data in tree models.
</para>
<glossseealso>model-view widget</glossseealso>
</glossdef>
</glossentry>
<glossentry id="container">
<glossterm>container</glossterm>
<glossdef>
<para>
A <glossterm linkend="widget">widget</glossterm> that contains
other widgets; in that case, the container is the
<emphasis>parent</emphasis> of the <emphasis>child</emphasis>
widgets. Some containers don't draw anything on their own,
but rather just organize their children's <glossterm
linkend="geometry">geometry</glossterm>; for example, #GtkVBox lays out
its children vertically without painting anything on its own. Other
containers include decorative elements; for example, #GtkFrame contains
the frame's child and a label in addition to the shaded frame it draws.
The base class for containers is #GtkContainer.
</para>
<glossseealso>
<glossterm linkend="container">widget</glossterm>
<glossterm linkend="container">geometry</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="display">
<glossterm>display</glossterm>
<glossdef>
<para>
GDK inherited the concept of display from the X window system,
which considers a display to be the combination
of a keyboard, a pointing device and one or more
<glossterm linkend="screen">screens</glossterm>.
Applications open a display to show windows and interact with the user.
In GDK, a display is represented by a #GdkDisplay.
</para>
</glossdef>
</glossentry>
<glossentry id="ellipsization">
<glossdef>
<para>
Ellipsization is the process of replacing some part
of a text by an ellipsis (usually "...") to make the
text fit in a smaller space. Pango can ellipsize text
at the beginning, at the end or in the middle.
</para>
</glossdef>
</glossentry>
<glossentry id="event">
<glossterm>event</glossterm>
<glossdef>
<para>
Events are the way in which GDK informs GTK+ about external events
like pointer motion, button clicks, key presses, etc.
</para>
</glossdef>
</glossentry>
<glossentry id="geometry">
<glossterm>geometry</glossterm>
<glossdef>
<para>
A <glossterm linkend="widget">widget's</glossterm> position
and size. Within its parent, this is called the widget's
<glossterm linkend="allocation">allocation</glossterm>.
</para>
</glossdef>
</glossentry>
<glossentry id="mapping">
<glossterm>mapping</glossterm>
<glossdef>
<para>
This is the step in a <glossterm
linkend="widget">widget's</glossterm> life cycle where it
actually shows the GdkWindows it created when it was
<glossterm linkend="realization">realized</glossterm>. When a
widget is mapped, it must turn on its
%GTK_MAPPED <link linkend="GtkWidgetFlags">flag</link>.
</para>
<para>
Note that due to the asynchronous nature of the X window
system, a widget's window may not appear on the screen
immediatly after one calls gdk_window_show():
you must wait for the corresponding map <glossterm
linkend="event">event</glossterm> to be received. You can do
this with the <link
linkend="GtkWidget-map-event"><methodname>GtkWidget::map-event</methodname>
signal</link>.
</para>
</glossdef>
</glossentry>
<glossentry id="model-column">
<glossterm>model column</glossterm>
<glossdef>
<para>
A column in a tree model, holding data of a certain type.
The types which can be stored in the columns of a model
have to be specified when the model is constructed, see
e.g. gtk_list_store_new().
</para>
<glossseealso>
<glossterm linkend="view-column">view column</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="model-view">
<glossterm>model-view widget</glossterm>
<glossdef>
<para>
These widgets follow the well-known model-view pattern, which separates
the data (the model) to be displayed from the component which does the
actual visualization (the view). Examples of this pattern in GTK+ are
the #GtkTreeView/#GtkTreeModel and #GtkTextView/#GtkTextBuffer
</para>
<para>
One important advantage of this pattern is that it is possible to
display the same model in multiple views; another one that the
separation of the model allows a great deal of flexibility, as
demonstrated by e.g. #GtkTreeModelSort or #GtkTreeModelFilter.
</para>
</glossdef>
</glossentry>
<glossentry id="no-window">
<glossterm>no-window widget</glossterm>
<glossdef>
<para>
A widget that does not have a GdkWindow of its own on which to
draw its contents, but rather shares its <glossterm
linkend="parent">parent's</glossterm>. This can be tested with
the gtk_widget_get_has_window() function. See
<xref linkend="window-no-window-widgets"/> for a detailed
description of this flag.
</para>
</glossdef>
</glossentry>
<glossentry id="parent">
<glossterm>parent</glossterm>
<glossdef>
<para>
A <glossterm linkend="widget">widget's</glossterm> parent is
the <glossterm linkend="container">container</glossterm>
inside which it resides.
</para>
</glossdef>
</glossentry>
<glossentry id="realization">
<glossterm>realization</glossterm>
<glossdef>
<para>
This is the step in a <glossterm
linkend="widget">widget's</glossterm> life cycle where it
creates its own GdkWindow, or otherwise associates itself with
its <glossterm linkend="parent">parent's</glossterm>
GdkWindow. If the widget has its own window, then it must
also attach a <glossterm linkend="style">style</glossterm> to
it. A widget becomes unrealized by destroying its associated
GdkWindow. When a widget is realized, it must turn on its
%GTK_REALIZED <link linkend="GtkWidgetFlags">flag</link>.
</para>
<para>
Widgets that don't own the GdkWindow on which they draw are
called <glossterm linkend="no-window">no-window widgets</glossterm>.
This can be tested with the GTK_WIDGET_NO_WINDOW() macro. Normally,
these widgets draw on their parent's GdkWindow.
</para>
<para>
Note that when a widget creates a window in its <link
linkend="gtkwidget-realize"><methodname>::realize()</methodname></link>
handler, it does not actually show the window. That is, the
window's structure is just created in memory. The widget
actually shows the window when it gets <glossterm
linkend="mapping">mapped</glossterm>.
</para>
</glossdef>
</glossentry>
<glossentry id="requisition">
<glossterm>requisition</glossterm>
<glossdef>
<para>
The size requisition of a <glossterm
linkend="widget">widget</glossterm> is the minimum amount of
space it requests from its <glossterm
linkend="parent">parent</glossterm>. Once the parent computes
the widget's final size, it gives it its <glossterm
linkend="allocation">size allocation</glossterm>.
</para>
<glossseealso>
<glossterm linkend="allocation">allocation</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="screen">
<glossterm>screen</glossterm>
<glossdef>
<para>
GDK inherited the concept of screen from the X window system,
which considers a screen to be a rectangular area, on which
applications may place their windows. Screens under X may have
quite dissimilar <glossterm linkend="visual">visuals</glossterm>.
Each screen can stretch across multiple physical monitors.
</para>
<para>
In GDK, screens are represented by #GdkScreen objects.
</para>
</glossdef>
</glossentry>
<glossentry id="style">
<glossterm>style</glossterm>
<glossdef>
<para>
A style encapsulates what GTK+ needs to know in order to draw
a widget. Styles can be modified with
<link linkend="gtk-Resource-Files">resource files</link>.
</para>
</glossdef>
</glossentry>
<glossentry id="toplevel">
<glossterm>toplevel</glossterm>
<glossdef>
<para>
A <glossterm linkend="widget">widget</glossterm> that does not
require a <glossterm linkend="parent">parent</glossterm> container.
The only toplevel widgets in GTK+ are #GtkWindow and widgets derived from it.
</para>
<glossseealso>
<glossterm linkend="container">container</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="unmap">
<glossterm>unmap</glossterm>
<glosssee><glossterm linkend="mapping">mapping</glossterm></glosssee>
</glossentry>
<glossentry id="unrealize">
<glossterm>unrealize</glossterm>
<glosssee><glossterm linkend="realization">realization</glossterm></glosssee>
</glossentry>
<glossentry id="view-column">
<glossterm>view column</glossterm>
<glossdef>
<para>
A displayed column in a tree view, represented by a
#GtkTreeViewColumn object.
</para>
<glossseealso>
<glossterm linkend="model-column">model column</glossterm>
</glossseealso>
</glossdef>
</glossentry>
<glossentry id="visual">
<glossterm>visual</glossterm>
<glossdef>
<para>
A visual describes how color information is stored in pixels.
A <glossterm linkend="screen">screen</glossterm> may support
multiple visuals. On modern hardware, the most common visuals
are truecolor visuals, which store a fixed number of bits
(typically 8) for the red, green and blue components of a color.
</para>
<para>
On ancient hardware, one may still meet indexed visuals, which
store color information as an index into a color map, or even
monochrome visuals.
</para>
</glossdef>
</glossentry>
<glossentry id="widget">
<glossterm>widget</glossterm>
<glossdef>
<para>
A control in a graphical user interface. Widgets can draw
themselves and process events from the mouse and keyboard.
Widget types include buttons, menus, text entry lines, and
lists. Widgets can be arranged into <glossterm
linkend="container">containers</glossterm>, and these take
care of assigning the <glossterm
linkend="geometry">geometry</glossterm> of the widgets: every
widget thus has a parent except those widgets which are
<glossterm linkend="toplevel">toplevels</glossterm>. The base
class for widgets is #GtkWidget.
</para>
<glossseealso>
<glossterm linkend="container">container</glossterm>
</glossseealso>
</glossdef>
</glossentry>
</glossary>
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