<refentry id="gtk-x11" revision="17 Jan 2002"> <refmeta> <refentrytitle>Using GTK+ on the X Window System</refentrytitle> <manvolnum>3</manvolnum> <refmiscinfo>GTK Library</refmiscinfo> </refmeta> <refnamediv> <refname>Using GTK+ on the X Window System</refname> <refpurpose> X11 aspects of using GTK+ </refpurpose> </refnamediv> <refsect1> <title>GTK+ for the X Window System</title> <para> On UNIX, the X backend is the default build for GTK+. So you don't need to do anything special when compiling it, and everything should "just work." </para> <para> To mix low-level Xlib routines into a GTK program, see <link linkend="gdk-X-Window-System-Interaction">GDK X Window System interaction</link> in the GDK manual. </para> <refsect2 id="x11-cmdline"> <title>X11-specific commandline options</title> <para> The X backend understands some additional command line arguments. </para> <formalpara> <title><systemitem>--display <replaceable>display</replaceable></systemitem></title> <para> The name of the X display to open instead of the one specified in the <envar>DISPLAY</envar> environment variable. </para> </formalpara> <formalpara> <title><systemitem>--screen <replaceable>screen_number</replaceable></systemitem></title> <para> The number of the screen within the default display. This overrides any screen number specified in the display name specified by by he <systemitem>--display</systemitem> command line option or the <envar>DISPLAY</envar> environment variable. If this screen cannot be opened, then GTK+ will fall back to the screen specified in the display name. This option is not useful interactively; the intended purposes is that when a program registers its command line with a <firstterm>session manager</firstterm> for later restarting, it can save the screen it is on, without having to worry if it might be restarted on a different display. </para> </formalpara> <formalpara> <title><systemitem>--sync</systemitem></title> <para> Makes all X requests synchronously. This is a useful option for debugging, but it will slow down the performance considerably. </para> </formalpara> <formalpara> <title><systemitem>--gxid-host <replaceable>host</replaceable></systemitem></title> <para> The host to contact the <application>gxid</application> daemon on; overrides the <link linkend="GXID"><envar>GXID_HOST</envar></link> environment variable. </para> </formalpara> <formalpara> <title><systemitem>--gxid-port <replaceable>port</replaceable></systemitem></title> <para> The port for the connection to <application>gxid</application>; overrides the <link linkend="GXID"><envar>GXID_PORT</envar></link> environment variable. This option is only available if GTK+ has been configured with <option>--gdk-target=x11</option>. </para> </formalpara> </refsect2> <refsect2 id="x11-envar"> <title>X11-specific environment variables</title> <para> The X backend can be influenced with some additional environment variables. </para> <formalpara id="GXID"> <title><envar>GXID_HOST</envar>, <envar>GXID_PORT</envar></title> <para> The host and port to contact the <application>gxid</application> daemon on. <application>gxid</application> is only necessary on X servers which don't support using the pointer and extension devices at once, and is only built if GTK+ is configured with <option>--with-xinput=gxi</option>. The <application>XFree86</application> and <application>Xorg</application> X servers don't have this restriction. </para> </formalpara> <formalpara> <title><envar>GDK_USE_XFT</envar></title> <para> If this variable is set to 1, GTK+ will use the Pango Xft backend instead of the X backend when possible (i.e. when the X server supports the XRender extension and Pango has been built with Xft support). </para> </formalpara> </refsect2> </refsect1> <refsect1 id="gtk-X11-arch"> <title>Understanding the X11 architecture</title> <para> People coming from a Windows or MacOS background often find certain aspects of the X Window System surprising. This section introduces some basic X concepts at a high level. For more details, the book most people use is called the <citetitle pubwork="book">Xlib Programming Manual</citetitle> by Adrian Nye; this book is volume one in the O'Reilly X Window System series. </para> <para> Standards are another important resource if you're poking in low-level X11 details, in particular the ICCCM and the Extended Window Manager Hints specifications. <ulink url="http://www.freedesktop.org/standards/">freedesktop.org</ulink> has links to many relevant specifications. </para> <para> The GDK manual covers <link linkend="gdk-X-Window-System-Interaction">using Xlib in a GTK program</link>. </para> <refsect2> <title>Server, client, window manager</title> <para> Other window systems typically put all their functionality in the application itself. With X, each application involves three different programs: the <firstterm>X server</firstterm>, the application (called a <firstterm>client</firstterm> because it's a client of the X server), and a special client called the <firstterm>window manager</firstterm>. </para> <para> The X server is in charge of managing resources, processing drawing requests, and dispatching events such as keyboard and mouse events to interested applications. So client applications can ask the X server to create a window, draw a circle, or move windows around. </para> <para> The window manager is in charge of rendering the frame or borders around windows; it also has final say on the size of each window, and window states such as minimized, maximized, and so forth. On Windows and MacOS the application handles most of this. On X11, if you wish to modify the window's state, or change its frame, you must ask the window manager to do so on your behalf, using an established <ulink url="http://www.freedesktop.org/standards/">convention</ulink>. </para> <para> GTK+ has functions for asking the window manager to do various things; see for example <link linkend="gtk-window-iconify">gtk_window_iconify()</link> or <link linkend="gtk-window-maximize">gtk_window_maximize()</link> or <link linkend="gtk-window-set-decorated">gtk_window_set_decorated()</link>. Keep in mind that <link linkend="gtk-window-move">gtk_window_move()</link> and window sizing are ultimately controlled by the window manager as well and most window managers <emphasis>will</emphasis> ignore certain requests from time to time, in the interests of good user interface. </para> <!-- May also want to explain DESKTOP_STARTUP_ID here. http://www.freedesktop.org/Standards/startup-notification-spec --> </refsect2> </refsect1> </refentry>