247 lines
9.8 KiB
XML
247 lines
9.8 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd"
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[
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<!ENTITY % defs SYSTEM "defs.ent"> %defs;
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]>
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<article id="appgroup">
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<articleinfo>
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<title>Description of the Application Group Extension</title>
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<subtitle>Implementation for the X11 Sample Server</subtitle>
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<authorgroup>
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<author>
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<firstname>Kaleb </firstname><surname>KEITHLEY</surname>
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<affiliation><orgname>FUJITSU Limited.</orgname></affiliation>
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</author>
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</authorgroup>
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<releaseinfo>X Version 11, Release &fullrelvers;</releaseinfo>
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<releaseinfo>Version 1.0</releaseinfo>
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<copyright><year>1996</year><holder>X Consortium</holder></copyright>
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<legalnotice>
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<para>
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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</para>
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<para>
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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</para>
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<para>
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THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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</para>
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<para>
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Except as contained in this notice, the name of the X Consortium shall
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not be used in advertising or otherwise to promote the sale, use or
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other dealings in this Software without prior written authorization
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from the X Consortium.
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</para>
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<para>X Window System is a trademark of The Open Group.</para>
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</legalnotice>
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<legalnotice>
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<para>WindowsNT is a trademark of Microsoft, Inc.</para>
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<para>Macintosh and Apple are trademarks of Apple Computer, Inc.</para>
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</legalnotice>
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<abstract>
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<para>
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The following document explains the server side of the Application
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Group Extension.
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</para>
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</abstract>
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</articleinfo>
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<para>
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To understand this document and the accompanying source code, you
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should know the C language, should be familiar with X server
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internals, and should also have a general knowledge of the X
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Window System.
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</para>
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<sect1 id="AppGroup_Server_Public_Functions">
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<title>AppGroup Server Public Functions</title>
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<para>
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The AppGroup extension adds seven new functions that are called
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from elsewhere in the server. They are: XagExtensionInit,
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XagDefaultColormap, XagRootVisual, XagLeader, XagIsControlledRoot,
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XagConnectionInfo, XagCallClientStateChange.
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</para>
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<para>
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XagExtensionInit is the extension initialization function called
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from InitExtension in mi/miinitext.c. Note that an new resource
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type, RT_APPGROUP, is created, specifying the destructor function
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XagAppGroupFree.
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</para>
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<para>
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XagDefaultColormap returns the colormap ID that was specified in
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the creation of the AppGroup. Any time CopyFromParent is specified
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for a top-level window's colormap, i.e. in a CreateWindow or
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ChangeWindowAttributes request, this function is called to see
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if there is an AppGroup specific colormap to use. If there is
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one, its ID is returned, otherwise None is returned.
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</para>
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<para>
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XagRootVisual returns the visual ID that was specified in the
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creation of the Appgroup. Like XagDefaultColormap, when CopyFromParent
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is specified for a top-level window's visual in a CreateWindow
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request, this function is called to see if there is an AppGroup
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specific visual to use. If there is one, its ID is returned,
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otherwise 0 (zero) is returned.
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</para>
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<para>
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XagLeader returns the ClientPtr of the client that is the AppGroup
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Leader. Normally when an application maps or configures a top-level
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window a MapRequest or ConfigureRequest event is delivered to the
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client, e.g. a window manager, that has selected SubstructureRedirect
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on the root window. However, when the application is part of an
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AppGroup, the MapRequest and ConfigureRequest events are delivered
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to the AppGroup Leader instead.
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</para>
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<para>
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XagIsControlledRoot returns a boolean: True if the window is a
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top-level window of a client in an AppGroup, False otherwise.
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In a combined server, i.e. one that provides both UI and printing,
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the application may create and map windows on the "printing"
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screens; thus it becomes necessary to discriminate between the
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AppGroup's root window and other root windows. If an AppGroup
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member creates and maps a [top-level] window then the window's
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parent [the root window] is tested to determine whether to send
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MapRequest or ConfigureRequest events to the AppGroup Leader to
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to some other client.
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</para>
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<para>
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In the trivial case XagIsControlledRoot returns True if the parent
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window has no parent itself, i.e. it is a root window. In the case
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where the application is embedded, indicated by the singleScreen
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attribute being True, the parent's drawable ID is compared to the
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AppGroup's root window ID, and if it is the same, True is returned.
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If neither case is true, then False is returned.
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</para>
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<para>
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XagConnectionInfo returns an abreviated version of the connection
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setup information. When an embedded AppGroup is created the server
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returns only the information about the [UI] screen that the
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application is embedded within in the connection setup in order to
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prevent the application from creating windows on other screens;
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thus attempting to guarantee that any window that should be embedded
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can be reparented into the AppGroup Leader's window hierarchy.
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</para>
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<para>
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XagCallClientStateChange is called to invoke the extension's client
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state change callback additional times as necessary -- currently
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only once, after the auth data becomes available between
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ClientStateInitial and ClientStateConnected. Client state change
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callbacks were introduced in the Record extension, which specifies
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when the callbacks are invoked. Unfortunately the points at which
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they are called are not necessarily the best as far as the AppGroup
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Extension is concerned. Adding an additional state and calling all
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the callbacks works too, however this seemed unnecessary overkill.
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</para>
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</sect1>
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<sect1 id="AppGroup_Server_Private_APIs">
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<title>AppGroup Server Private APIs</title>
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<para>
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The AppGroup extension adds the following functions which are
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private to the extension: ProcXagDispatch and SProcXagDispatch,
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ProcXagQueryVersion and SProcXagQueryVersion, ProcXagCreate and
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SProcXagCreate, ProcXagDestroy and SProcXagDestroy,
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ProcGetAttr and SProcGetAttr, ProcXagQuery and SProcXagQuery,
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ProcXagCreateAssoc and SProcXagCreateAssoc, ProcXagDestroyAssoc
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and SProcXagDestroyAssoc, XagResetProc, and XagAppGroupFree.
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</para>
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<para>
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The ProcXagDispatch, SProcXagDispatch, and XagResetProc functions
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should be familiar to anyone familiar with X server internals and
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I won't elaborate on them here. Similarly the wrapper functions:
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SProcXagQueryVersion, SProcXagCreate, SProcXagDestroy, SProcXagGetAttr,
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SProcXagQuery, SProcXagCreateAssoc, and SProcXagDestroyAssoc, as
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wrappers which handle swapping integer data into the host's byte
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order will not be explained in any detail.
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</para>
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<para>
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ProcXagQueryVersion returns the major and minor versions of the
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AppGroup extension supported by the server.
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</para>
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<para>
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ProcXagCreate creates an AppGroup. A new record in a linked list
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of AppGroups is allocated and initialized. The attributes from the
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request are validated and copied to the AppGroup record. If necessary
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an abbreviated version of the connection setup information is compiled
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and also stored in the AppGroup record. The first time an AppGroup
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is created a client-state-change callback is registered and a
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reference count is incremented.
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</para>
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<para>
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ProcXagDestroy destroys an AppGroup an AppGroup by calling
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FreeResource specifying the AppGroup ID. This will result in
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the destructor function XagAppGroupFree being called. The
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reference count is decremented and when it reaches zero the
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client-state-change callback is deleted.
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</para>
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<para>
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ProcXagGetAttr returns the AppGroup Attributes to the requesting
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client.
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</para>
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<para>
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ProcXagQuery returns the AppGroup ID of an arbitrary resource to
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the requesting client.
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</para>
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<para>
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ProcXagCreateAssoc creates an association between an X window ID
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and system-specific data. In native X this functionality is
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unnecessary but for various personal computers, e.g. Macintosh,
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OS/2, and MS-Windows it is necessary to associate an X window ID
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with the system's native window identifier so that when the
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AppGroup Leader issues a ReparentWindow request the personal
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computer X server can lookup the system-specific window ID and
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make the necessary function call(s) with it.
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</para>
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<para>
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ProcXagDestroyAssoc destroys the association created with
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ProcXagCreateAssoc.
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</para>
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<para>
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XagResetProc removes the client-state-change callback, sets the
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reference count to zero, and frees all the AppGroup records in
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the linked list by calling XagAppGroupFree.
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</para>
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<para>
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XagAppGroupFree calls CloseDownClient for each client in an
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AppGroup if the AppGroup has a leader, unlinks the AppGroup
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record from the linked list, frees allocated memory referenced
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by the record, and finally frees the record itself.
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</para>
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</sect1>
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<sect1 id='Known_Problems_in_this_release'>
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<title>Known Problems in this release.</title>
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<para>
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In a combined UI/Print server the connection setup returned to an
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embedded application will not have information about the print
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screens.
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</para>
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<para>
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The LBX proxy caches connection setup information and will return
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incorrect connection setup information to an embedded client.
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</para>
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</sect1>
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</article>
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