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gtk 开发手册和参考文档。 包括gtk glib gdk等

            termed "ghosted" or "inactive").
          </p>
          <p>
            <tt class="FUNCTION">gtk_widget_set_sensitive()</tt>
            (<a href="z57.html#FL-SETSENSITIVE">Figure 25</a>)
            changes a widget's sensitivity.
          </p>
          <div class="FIGURE">
            <a name="FL-SETSENSITIVE"></a>
            <div class="FUNCSYNOPSIS">
              <a name="FL-SETSENSITIVE.SYNOPSIS"></a>
              <table border="0" bgcolor="#E0E0E0" width="100%">
                <tr>
                  <td>
<pre class="FUNCSYNOPSISINFO">
#include &lt;gtk/gtkwidget.h&gt;
</pre>
                  </td>
                </tr>
              </table>
              <p>
                <code><code class="FUNCDEF">void <tt class=
                "FUNCTION">
                gtk_widget_set_sensitive</tt></code>(GtkWidget* <tt
                class="PARAMETER"><i>widget</i></tt>, gboolean <tt
                class="PARAMETER"><i>setting</i></tt>);</code>
              </p>
            </div>
            <p>
              <b>Figure 25. Changing Sensitivity</b>
            </p>
          </div>
          <p>
            By default sensitivity is set to <span class=
            "STRUCTNAME">TRUE</span>. A widget is only "really"
            sensitive if all its parents are sensitive; that is,
            you can make an entire container full of widgets
            (in)sensitive by setting the sensitivity of the
            container. The "real" sensitivity of a widget,
            including its parent's state, can be tested with the
            <tt class="FUNCTION">GTK_WIDGET_IS_SENSITIVE()</tt>
            macro. The sensitivity of the widget itself, which only
            matters if the widget's parent is sensitive, can be
            queried using <tt class="FUNCTION">
            GTK_WIDGET_SENSITIVE()</tt>. These are in <a href= 
            "z57.html#ML-ISSENSITIVE">Figure 26</a>.
          </p>
          <div class="FIGURE">
            <a name="ML-ISSENSITIVE"></a>
            <div class="FUNCSYNOPSIS">
              <a name="ML-ISSENSITIVE.SYNOPSIS"></a>
              <table border="0" bgcolor="#E0E0E0" width="100%">
                <tr>
                  <td>
<pre class="FUNCSYNOPSISINFO">
#include &lt;gtk/gtkwidget.h&gt;
</pre>
                  </td>
                </tr>
              </table>
              <p>
                <code><code class="FUNCDEF"><tt class="FUNCTION">
                GTK_WIDGET_IS_SENSITIVE</tt></code>(<tt class= 
                "PARAMETER"><i>widget</i></tt>);</code>
              </p>
              <p>
                <code><code class="FUNCDEF"><tt class="FUNCTION">
                GTK_WIDGET_SENSITIVE</tt></code>(<tt class= 
                "PARAMETER"><i>widget</i></tt>);</code>
              </p>
            </div>
            <p>
              <b>Figure 26. Sensitivity</b>
            </p>
          </div>
        </div>
        <div class="SECT3">
          <h3 class="SECT3">
            <a name="SEC-FOCUSWIDGET">Focus</a>
          </h3>
          <p>
            Within each toplevel window, one widget at a time may
            have the <i class="FIRSTTERM">keyboard focus</i>. Any
            key events received by the toplevel window are
            forwarded to the focused widget. This is important
            because typing something on the keyboard should have
            only one effect---changing only one text entry field,
            for example.
          </p>
          <p>
            Most widgets will give some visual indication that they
            have the current focus. Using the default GTK+ theme,
            the focused widget is typically surrounded by a thin
            black frame. The user can move the focus between
            widgets, using the arrow keys or the Tab key. Focus can
            also move to a widget if the user clicks it.
          </p>
          <p>
            The concept of focus is important for keyboard
            navigation. For example, pressing Enter or the space
            bar "activates" many widgets if they have the focus;
            you can move between buttons with the Tab key, and
            press one with Space, for example.
          </p>
        </div>
        <div class="SECT3">
          <h3 class="SECT3">
            <a name="SEC-GRABS">Grabs</a>
          </h3>
          <p>
            Widgets can <i class="FIRSTTERM">grab</i> the pointer
            and keyboard away from other widgets. This essentially
            means that the widget becomes "modal"; input goes only
            to that widget, and the focus can't be changed to
            another widget. A typical reason to grab input is to
            create a modal dialog; if a window has the grab,
            interaction with other windows is blocked. Note that
            there is another, GDK-level "grab"; a GDK keyboard or
            pointer grab occurs on an X-server-wide basis---that
            is, other applications are unable to receive keyboard
            or mouse events. A widget grab is a GTK+ concept; it
            only grabs events away from other widgets in the same
            application.
          </p>
        </div>
        <div class="SECT3">
          <h3 class="SECT3">
            <a name="Z59">Default</a>
          </h3>
          <p>
            Each window may have at most one <i class="FIRSTTERM">
            default</i> widget. For example, dialogs typically have
            a default button which is activated when the user
            presses the Enter key.
          </p>
        </div>
        <div class="SECT3">
          <h3 class="SECT3">
            <a name="SEC-WIDGETSTATES">Widget States</a>
          </h3>
          <p>
            Widgets have <i class="FIRSTTERM">states</i> which
            determine their appearance:
          </p>
          <ul>
            <li>
              <p>
                <i class="FIRSTTERM">Normal</i>: just like it
                sounds.&#13;
              </p>
            </li>
            <li>
              <p>
                <i class="FIRSTTERM">Active</i>: a button is
                currently pressed in, or a check box is currently
                checked, for example.&#13;
              </p>
            </li>
            <li>
              <p>
                <i class="FIRSTTERM">Prelight</i>: the mouse is
                over the widget (and typically clicking would have
                some effect). Buttons "highlight" when you move
                over them, for example.&#13;
              </p>
            </li>
            <li>
              <p>
                <i class="FIRSTTERM">Selected</i>: the widget is in
                a list or other set of alternatives, and is the
                currently selected option.&#13;
              </p>
            </li>
            <li>
              <p>
                <i class="FIRSTTERM">Insensitive</i>: the widget is
                "ghosted," inactive, or unresponsive; it will not
                respond to input.&#13;
              </p>
            </li>
          </ul>
          <p>
            The exact meaning and visual representation of a given
            state depends on the particular widget and the current
            theme. You can access the state of the widget <tt
            class="FUNCTION">GTK_WIDGET_STATE()</tt> (<a href= 
            "z57.html#ML-WIDGETSTATE">Figure 27</a>). This macro
            returns one of the constants <span class="STRUCTNAME">
            GTK_STATE_NORMAL</span>, <span class="STRUCTNAME">
            GTK_STATE_ACTIVE</span>, <span class="STRUCTNAME">
            GTK_STATE_PRELIGHT</span>, <span class="STRUCTNAME">
            GTK_STATE_SELECTED</span>, or <span class="STRUCTNAME">
            GTK_STATE_INSENSITIVE</span>.
          </p>
          <div class="FIGURE">
            <a name="ML-WIDGETSTATE"></a>
            <div class="FUNCSYNOPSIS">
              <a name="ML-WIDGETSTATE.SYNOPSIS"></a>
              <table border="0" bgcolor="#E0E0E0" width="100%">
                <tr>
                  <td>
<pre class="FUNCSYNOPSISINFO">
#include &lt;gtk/gtkwidget.h&gt;
</pre>
                  </td>
                </tr>
              </table>
              <p>
                <code><code class="FUNCDEF"><tt class="FUNCTION">
                GTK_WIDGET_STATE</tt></code>(<tt class=
                "PARAMETER"><i>widget</i></tt>);</code>
              </p>
            </div>
            <p>
              <b>Figure 27. State Accessor</b>
            </p>
          </div>
        </div>
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