1\input texinfo @c -*-texinfo-*- 2@c A FAQ for GNUstep 3 4@node Top, Compatibility, (dir), (dir) 5@chapter GNUstep Frequently Asked Questions with Answers 6 7Last updated @today{}. 8Please send corrections to @email{gnustep-maintainer@@gnu.org}. Also look 9at the user FAQ for more user oriented questions. 10 11@menu 12* Compatibility:: 13* Compiling and Developing:: 14* GNU Objective C Compiler and Runtime:: 15* GNUstep Base Library:: 16* GNUstep GUI Library:: 17* GNUstep DisplayGhostScript Server:: 18@end menu 19 20@c **************************************************************** 21@c Compiling 22@node Compatibility, Compiling and Developing, Top, Top 23@section Compatibility 24 25@menu 26* Is it easy to port OPENSTEP programs to GNUstep?:: 27* How about porting between Cocoa and GNUstep?:: 28* Tools for porting:: 29* Can I transfer archived data from GNUstep to Cocoa?:: 30* Does distributed objects work between GNUstep and Cocoa?:: 31* Is there an Interface Builder for GNUstep?:: 32* Can I use my original NIB files?:: 33* Can one use the hybrid "Objective-C++":: 34* Is there a plan to support Java/YellowBox Bindings?:: 35* What if I compile GNUstep under OPENSTEP/MacOS X?:: 36* Is the Objective C API for GTK related?:: 37* How about implementing parts of the Application Kit with GTK?:: 38@end menu 39 40@node Is it easy to port OPENSTEP programs to GNUstep?, How about porting between Cocoa and GNUstep?, Compatibility, Compatibility 41@subsection Is it easy to port OPENSTEP programs to GNUstep? 42 43It is probably easy for simple programs. There are some portability 44tools to make this easier, or rewrite 45the Makefiles yourself. You will also have to translate the NIB files 46(if there are any) to GNUstep model files using the nib2gmodel program 47(from @url{ftp://ftp.gnustep.org/pub/gnustep/dev-apps}). 48 49@node How about porting between Cocoa and GNUstep?, Tools for porting, Is it easy to port OPENSTEP programs to GNUstep?, Compatibility 50@subsection How about porting between Cocoa and GNUstep? 51 52It's easier from GNUstep to Cocoa than Cocoa to GNUstep. Cocoa is 53constantly changing, much faster than GNUstep could hope to keep 54up. They have added extensions and new classes that aren't available in 55GNUstep yet. Plus there are some other issues. If you start with 56Cocoa: 57 58@itemize @bullet 59@item Use #ifndef GNUSTEP for Apple only code. 60@item Do not use CoreFoundation 61@item Do not use Objective-C++ (except with gcc 4.1 or later) 62@item Do not use Quicktime or other proprietary extension 63@item GNUstep should be able to read Cocoa nib files automatically, so there 64is no need to port these, although you might want to have GNUstep specific 65versions of them anyway. 66@end itemize 67 68See also @url{http://mediawiki.gnustep.org/index.php/Writing_portable_code} 69for more information. 70 71@node Tools for porting, Can I transfer archived data from GNUstep to Cocoa?, How about porting between Cocoa and GNUstep?, Compatibility 72@subsection Tools for porting 73 74While the programming interface should be almost transparent between 75systems (expect for the unimplemented parts, of course), there are a 76variety of other files and tools that are necessary for porting 77programs. 78 79@table @samp 80@item nib2gmodel 81This program coverts nib files from any system, such as OPENSTEP to 82a gmodel format file. Gmodel can be read directly by GNUstep or you can 83convert this to a more GNUstep-native gorm format (using the Gorm interface 84modeller). Note this is not necessary for Cocoa nibs - GNUstep can read these 85directly. 86 87@item Renaissance 88GNUstep Renaissance allows you to describe your user 89interfaces (that is, the windows in your application, and the buttons, 90boxes, textfields, etc in the windows) in simple and intuitive XML 91files, using an open, standard format describing the logic of the 92interface. It has a number of advantages over the proprietary nib format: 93portability, open standard, easy localization, themeability, and 94intelligent autolayout. 95 96@item Gorm 97The equivalent of the Interface Builder in GNUstep. It might be easier to 98just recreate the interface using Gorm rather than dealing with 99translations. 100 101@item OpenStep2GNUConverter and nfmake 102Two programs that allow you to convert PB files to GNUstep makefiles or 103compile a program on GNUstep directly from PB files. They probably work 104only for OPENSTEP systems and are a little out-of-date. 105 106@item StepTalk 107A portable scripting environment that lets your do scripting in almost 108any language you like. 109 110@end table 111 112@node Can I transfer archived data from GNUstep to Cocoa?, Does distributed objects work between GNUstep and Cocoa?, Tools for porting, Compatibility 113@subsection Can I transfer archived data from GNUstep to Cocoa? 114 115Apple's archiving format is proprietary and not documented, so this 116poses a problem for anyone wanting to implement compatibility with it. 117However, even if we reverse engineered the format, there are enough 118differences between the class and ivar layouts to make this sort of 119compatibility difficult. Not to mention the fact that we would 120constantly have to keep up with the changes Apple made. 121 122The new keyed archiving using XML file formats is much more portable, 123and GNUstep is trying to maintain compatibility with Apple with this 124type of archiving. 125 126@node Does distributed objects work between GNUstep and Cocoa?, Is there an Interface Builder for GNUstep?, Can I transfer archived data from GNUstep to Cocoa?, Compatibility 127@subsection Does distributed objects work between GNUstep and Cocoa? 128 129See the answer to the previous question (on archive compatibility) for 130why this won't work either. 131 132@node Is there an Interface Builder for GNUstep?, Can I use my original NIB files?, Does distributed objects work between GNUstep and Cocoa?, Compatibility 133@subsection Is there an Interface Builder for GNUstep? 134 135There is an Interface Builder for GNUstep called Gorm. A lot of work 136has been put into it and it works very well. You can download it from 137the ftp site or via http. The Project Manager ProjectCenter is also 138available. 139 140@node Can I use my original NIB files?, Can one use the hybrid "Objective-C++", Is there an Interface Builder for GNUstep?, Compatibility 141@subsection Can I use my original NIB files? 142 143 No - NeXT/Apple never documented their nib format, so GNUstep supports 144both the 'gmodel' format (which stores information as text 145(property-lists) and can therefore be edited 'by hand') and binary 146archive format (which can be edited by Gorm). There IS a conversion 147tool called nib2gmodel that can be compiled under OPENSTEP to convert 148nib files to GNUstep gmodel files. 149 150The current version of gui supports reading nib files created as of 10.2. 151If you have nib files which are older than this, you can convert them by 152loading them into Interface Builder, going to the "file" second and saving 153the nib using the "10.2 or later format." 154 155@node Can one use the hybrid "Objective-C++", Is there a plan to support Java/YellowBox Bindings?, Can I use my original NIB files?, Compatibility 156@subsection Can one use the hybrid "Objective-C++" 157 158Yes gcc 4.1 has support for this. 159 160@node Is there a plan to support Java/YellowBox Bindings?, What if I compile GNUstep under OPENSTEP/MacOS X?, Can one use the hybrid "Objective-C++", Compatibility 161@subsection Is there a plan to support the Java/YellowBox Bindings? 162 163Yes. The GNUstep Java library/bridge called JIGS is available now. JIGS 164is a free (LGPL) Java Interface for GNUstep; it can automatically wrap 165Objective-C libraries based on GNUstep, making them accessible directly 166to the Java programmer as if they were Java libraries. As a side effect, 167it is also possible to use the whole engine in the reverse way: JIGS 168provides a high level API to allow Objective-C programmers to start java 169virtual machines inside GNUstep Objective-C code and access java objects 170in the java virtual machine transparently, as if they were objective-C 171objects. 172 173@node What if I compile GNUstep under OPENSTEP/MacOS X?, Is the Objective C API for GTK related?, Is there a plan to support Java/YellowBox Bindings?, Compatibility 174@subsection What if I compile GNUstep under OPENSTEP/MacOS X? 175 176GNUstep uses different backends to provide the same functionality as 177Display Postscript. While someone could write a backend library to 178provide the interface, nobody has bothered to date. 179 180 You can, however, use a GNUstep program with an X11 server running 181on MacOSX. 182 183@node Is the Objective C API for GTK related?, How about implementing parts of the Application Kit with GTK?, What if I compile GNUstep under OPENSTEP/MacOS X?, Compatibility 184@subsection Is the Objective C API for GTK related? 185 186 No. GNUstep applications provide their GUI via the OpenStep 187API, which provides fully object-oriented access to GUI manipulation. 188 189 The object-oriented nature of the libraries and language make it much easier 190for new users to create their own subclasses rather than simply using the 191supplied widgets as in other frameworks. 192 193@node How about implementing parts of the Application Kit with GTK?, , Is the Objective C API for GTK related?, Compatibility 194@subsection How about implementing parts of the Application Kit with GTK? 195 196 Yes and No - The GNUstep architecture provides a single, 197platform-independent, API for handling all aspects of GUI interaction 198(implemented in the gstep-gui library), with a backend architecture 199that permits you to have different display models (display postscript, 200X-windows, win32, berlin ...) while letting you use the same code 201for printing as for displaying. Use of GTK in the frontend gui 202library would remove some of those advantages without adding any. 203 204That being said, a backend library could be implemented using gtk 205if anyone wanted to do so. Since the frontend library handles most 206of the work involved in implementing the OpenStep API, the backend 207is a relatively thin layer and the advantages of GTK over direct 208xlib or win32 calls is likely to be minimal. If/when GTK is ported 209to more systems, a backend written using it could be a valuable 210asset - volunteers are, as always, welcome. 211 212 213@c **************************************************************** 214@c Compiling 215@node Compiling and Developing, GNU Objective C Compiler and Runtime, Compatibility, Top 216@section Compiling and Developing 217 218@menu 219* How can I get started programming?:: 220* How can I help with GNUstep?:: 221* Helping develop GNUstep:: 222* Helping document GNUstep:: 223* How do I assign my contribution?:: 224* How do I update the task list?:: 225* How do I start writing tests?:: 226* How do I start writing applications?:: 227* How can I help with the GNUstep website?:: 228* Why doesn't GDB support Objective-C?:: 229@end menu 230 231@node How can I get started programming?, How can I help with GNUstep?, Compiling and Developing, Compiling and Developing 232@subsection How can I get started programming? 233 234 Good question. Read the tutorials at the GNUstep web site. Also look at 235Apple's documentation (pointers in the Resources section on the GNUstep web 236site.) 237 238@node How can I help with GNUstep?, Helping develop GNUstep, How can I get started programming?, Compiling and Developing 239@subsection How can I help with GNUstep? 240 241@enumerate 242@item Write/debug library code 243@item Write documentation 244@item Update the task list and library headers 245@item Write applications 246@end enumerate 247 248Let people know what you are doing. Break your project up into 249the smallest units you can. Feed back frequent updates to the 250maintainers. Ask questions in the discussion mailing list. 251 252Do remember that any changes beyond a few lines of code (or 253documentation) require a disclaimer or copyright assignment to the 254Free Software Foundation before they can be incorporated into the 255project. Get in touch with the GNUstep maintainer about this. 256 257Don't start with large-scale reorganization of anything - instead, 258get a general idea in mind of what you want to do, and proceed as 259much as possible with incremental changes that don't break anything 260- that way you can make those incremental changes available to the 261rest of the community at frequent intervals. 262 263Don't be afraid to give up - there is no shame in finding out that 264you have take on too large/complex a project. It's much better to 265'resign' and take on a smaller job than to just stop without telling 266anyone. 267 268Please document the code you add or change (using autogsdoc comments 269that begin with a slash and two asterices). But PLEASE, do not copy from 270the Apple documentation or any other copyrighted documentation. 271 272 273@node Helping develop GNUstep, Helping document GNUstep, How can I help with GNUstep?, Compiling and Developing 274@subsection Helping develop GNUstep 275 276There is plenty of unimplemented stuff in the gui library and 277backend libraries that volunteers can work on - just browse through 278the code and see if it conforms to the documentation. 279 280Specific tasks are noted in the developers section on the GNUstep 281website. 282 283Once you have coded something, you could always write a testcase 284and documentation for it :-) 285 286@node Helping document GNUstep, How do I assign my contribution?, Helping develop GNUstep, Compiling and Developing 287@subsection Helping document GNUstep 288 289All class documentation is written directly in the source code itself 290and translated using the autogsdoc program. See the source code and 291documentation for autogsdoc for information on documenting the classes. 292 293Newcomers could write documentation for individual classes by 294comparing the OpenStep specification, the MacOS-X documentation, 295and the GNUstep source. Documentation should clearly note where 296individual methods are specific to OpenStep, MacOS-X or are GNustep 297extensions. 298 299More experienced people could write documentation on general 300programming topics, and tutorials for new users. 301 302Anyone willing to write documentation, either tutorials for using 303GNUstep, or reference documentation for individual classes, should 304either write it in gsdoc or as plain ascii text for someone else to 305format into gsdoc. 306 307GNUstep documentation should have copyright assigned to the Free 308Software Foundation. 309 310@node How do I assign my contribution?, How do I update the task list?, Helping document GNUstep, Compiling and Developing 311@subsection How do I assign my contribution? 312 313Everyone who contributes more than 20 lines of code or so needs to 314sign a copyright assignment so that the FSF can have legal control of 315the copyright. This makes it easier to defend against any copyright 316infringement suits. Contact the GNUstep maintainer for instructions 317on how to do this or download and fill out the form 318@url{http://www.gnustep.org/resources/request-assign.future} 319(instructions are included). 320 321 322@node How do I update the task list?, How do I start writing tests?, How do I assign my contribution?, Compiling and Developing 323@subsection How do I update the task list? 324 325 The task list (@url{http://savannah.gnu.org/pm/?group_id=99}) is 326supposed to tell people what jobs are waiting to be done. Feel free to 327add to it or update the tasks that are there (you need to create a login 328for yourself first). 329 330One job of major importance that pretty much anyone can do is to 331look for jobs to add to the task list. In the case of methods from 332the OpenStep specification or the MacOS-X documentation not being 333present in the GNUstep libraries, it is also helpful to add the 334method prototypes to the library header files. 335 336Send any changes or additions to @email{bug-gnustep@@gnu.org}. 337 338A beginner can look through the MacOS-X documentation, the OpenStep 339specification and the GNUstep source and contribute task items. 340 341If a class or method is in MacOS-X and OpenStep but is not in 342GNUstep - it's a high priority TODO and should at least be added 343to the GNUstep headers and a dummy version added to the source with 344a FIXME comment. 345 346If a class or method is in MacOS-X but not OpenStep or GNUstep - 347it's a low priority TODO. It should be added to the GNUstep headers 348bracketed in @code{#ifndef STRICT_OPENSTEP} 349 350If a class or method is in OpenStep but not in MacOS-X or GNUstep 351- it's a low priority TODO. It should be added to the GNUstep 352headers bracketed in @code{#ifndef STRICT_MACOS_X} 353 354There are a couple of people working on this already, so it's a 355good idea to get in touch with Greg, Adam or Richard to coordinate efforts. 356 357@node How do I start writing tests?, How do I start writing applications?, How do I update the task list?, Compiling and Developing 358@subsection How do I start writing tests? 359 360 You can write testcases - where the libraries fail tests, you 361could either fix the problem, or add it to the task list. 362 363To write testcases, you need to use svn to install the latest 364GNUstep sourcecode you can find. Then checkout the 365'gnustep/tools/testsuite' module from svn. 366 367@node How do I start writing applications?, How can I help with the GNUstep website?, How do I start writing tests?, Compiling and Developing 368@subsection How do I start writing applications? 369 370 You can either look at the links on the GNUstep website for 371applications that have been started, and email their owners to 372volunteer to help, or you can start your own project. 373 374@node How can I help with the GNUstep website?, Why doesn't GDB support Objective-C?, How do I start writing applications?, Compiling and Developing 375@subsection How can I help with the GNUstep website? 376 377Talk to Adam Fedor @email{fedor@@gnu.org}, the maintainer. 378 379The GNUstep website is kept as a CVS module, but the largest portions 380of it (the FAQ and the Documentation) are actually 381generated from files in the individual GNUstep packages. 382Many highly changeable portions are kept on the Wiki, so anyone can change 383these (first you need to get write access, though). 384 385If you want to update the FAQ or documentation - grab 386the latest snapshot of the GNUstep core you can find, update it 387from the svn repository, and work with the contents of the appropriate 388documentation directory. 389 390If you want to work on other parts of the website, you can grab a copy 391of the website via anonymous CVS. See 392@url{http://savannah.gnu.org/cvs/?group_id=99} for instructions on how 393to do that. 394 395The main task with the website is to figure out which bits are 396out-of-date (or wrong) and update/mark-as-outdated as required. 397 398@node Why doesn't GDB support Objective-C?, , How can I help with the GNUstep website?, Compiling and Developing 399@subsection Why doesn't GDB support Objective-C? 400 401As of GDB 6.0, gdb supports debugging of Objective-C code. 402 403@c ------------------------------------------------------------------- 404 405@node GNU Objective C Compiler and Runtime, GNUstep Base Library, Compiling and Developing, Top 406@section GNU Objective C Compiler and Runtime 407 408@menu 409* What is the Objective C Runtime?:: 410@end menu 411 412@node What is the Objective C Runtime?, , GNU Objective C Compiler and Runtime, GNU Objective C Compiler and Runtime 413@subsection What is the Objective C Runtime? 414 415The Objective C Runtime Library provides C functions and data structures 416required to execute an Objective C program. 417 418The GNU Objective C Runtime Library offers everything NeXT's runtime 419does, including Categories, Protocols, @samp{+poseAs:}, thread-safety, 420class initialization on demand, delayed loading of classes, and 421initialization of static instances (such as @@""-style string objects). 422 423It also has several differences over NeXT's implementation: 424 425@itemize @bullet 426 427@item GNU's runtime provides ``selector-types'' along with each 428selector; NeXT's does not. A selector-type is a string that describes 429the C variable types for the method's return and argument values. Among 430other uses, selector-types is extremely helpful for fast distributed 431objects implementations, (see GNUstep Base Library Section, below). 432 433@item Many of the GNU functions have different names than their 434corresponding NeXT functions; the GNU names conform to the GNU coding 435standards. The GNUstep base library contains a compatibility header that 436works with both runtimes. You should use functions there or use OpenStep 437Foundation methods/functions instead of the basic 438runtime functions so that you code can run with either system. 439 440Apple has recently added new functionality to their runtime, including 441built-in exception handling, etc. Hopefully these will be ported to the 442GNU runtime in the future. 443 444@end itemize 445 446@c ------------- GNU Compiler and Objective C Runtime Library ------- 447 448@node GNUstep Base Library, GNUstep GUI Library, GNU Objective C Compiler and Runtime, Top 449@section GNUstep Base Library 450 451@menu 452* What is the GNUstep Base Library?:: 453* What is base's current state of development?:: 454* What are the features of GNU Distributed Objects?:: 455@end menu 456 457@node What is the GNUstep Base Library?, What is base's current state of development?, GNUstep Base Library, GNUstep Base Library 458@subsection What is the GNUstep Base Library? 459 460The GNUstep Base Library is a library of general-purpose, non-graphical 461Objective C objects. For example, it includes classes for strings, 462object collections, byte streams, typed coders, invocations, 463notifications, notification dispatchers, moments in time, network ports, 464remote object messaging support (distributed objects), and event loops. 465 466It provides functionality that aims to implement the non-graphical 467portion of the OpenStep standard (the Foundation library). 468 469@node What is base's current state of development?, What are the features of GNU Distributed Objects?, What is the GNUstep Base Library?, GNUstep Base Library 470@subsection What is its current state of development? 471 472GNUstep base is currently stable and, to the best of our knowledge, 473implements all of the OpenStep functionality (except for a few classes 474that we feel are not useful). It also implements most all of the new 475Cocoa classes. However we do some things, like scripting, differently, 476so we don't implement all the Cocoa classes. 477 478@node What are the features of GNU Distributed Objects?, , What is base's current state of development?, GNUstep Base Library 479@subsection What are the features of GNU Distributed Objects? 480 481GNU Distributed Objects has many of the features of other distributed 482objects implementations, but, since it is free software, it can be 483ported to platforms for which other distributed objects implementations 484are not available. 485 486[ NOTE: The GNU distributed object facilities have the same ease-of-use 487as Apple's; be warned, however, that they are not compatible with each 488other. They have different class hierarchies, different instance 489variables, different method names, different implementation strategies 490and different network message formats. You cannot communicate with a 491Apple NSConnection using a GNU NSConnection. 492 493Here are some differences between GNU distributed objects and Apple's 494distributed objects: Apple NSDistantObject asks it's remote 495target for the method encoding types and caches the results; GNU 496NSDistantObject gets the types directly from the local GNU "typed selector" 497mechanism if the information is known locally and only queries the remote 498target or caching encoding types when using a method that is not known to 499the local process. The NSProxy for the remote root object always has name 500and, once set, you cannot change the root object of a NSConnection; the GNU 501Proxy for the remote root object has a target address value just like 502all other Proxy's, and you can change the root object as many times as 503you like. ]. 504 505@c --------------------------GNUstep Base Library---------------------- 506 507@node GNUstep GUI Library, GNUstep DisplayGhostScript Server, GNUstep Base Library, Top 508@section GNUstep GUI Library 509 510@menu 511* What is the GUI Library?:: 512* Explain the organization of the front- and back-ends:: 513* What is the current state of development of the front-end?:: 514* What is the current state of development of the back-ends?:: 515@end menu 516 517@node What is the GUI Library?, Explain the organization of the front- and back-ends, GNUstep GUI Library, GNUstep GUI Library 518@subsection What is the GUI Library? 519 520The GNUstep GUI Library is a library of objects useful for writing 521graphical applications. For example, it includes classes for drawing 522and manipulating graphics objects on the screen: windows, menus, 523buttons, sliders, text fields, and events. There are also many 524peripheral classes that offer operating-system-independent interfaces to 525images, cursors, colors, fonts, pasteboards, printing. There are also 526workspace support classes such as data links, open/save panels, 527context-dependent help, spell checking. 528 529It provides functionality that aims to implement the @samp{AppKit} 530portion of the OpenStep standard. However the implementation has 531been written to take advantage of GNUstep enhancements wherever possible. 532 533 534@node Explain the organization of the front- and back-ends, What is the current state of development of the front-end?, What is the GUI Library?, GNUstep GUI Library 535@subsection Explain the organization of the front- and back-ends 536 537The GNUstep GUI Library is divided into a front- and back-end. The 538front-end contains the majority of implementation, but leaves out the 539low-level drawing and event code. A back-end can override whatever 540methods necessary in order to implement low-level drawing event 541receiving. Different back-ends will make GNUstep available on various 542platforms. The default GNU back-end will run on top of X Windows. 543Other back-ends could allow GNUstep to run on OpenGL and WIN32 544graphics/event platforms. Much work will be saved by this clean 545separation between front- and back-end, because it allows different 546platforms to share the large amount of front-end code. 547 548@node What is the current state of development of the front-end?, What is the current state of development of the back-ends?, Explain the organization of the front- and back-ends, GNUstep GUI Library 549@subsection What is the current state of development of the front-end? 550 551Many of the classes are well implemented, if not thoroughly tested. 552See the GNUstep web sites and read status information contained in the 553distribution for the most up-to-date information. 554 555@node What is the current state of development of the back-ends?, , What is the current state of development of the front-end?, GNUstep GUI Library 556@subsection What is the current state of development of the back-ends? 557 558There are several backends currently available: 559 560@table @samp 561@item xlib 562This backend runs on X11 and uses standard xlib 563calls for implementing drawing. It works well, but is limited in many 564areas due to the limitations of xlib drawing. 565@item art 566This is a very good backend that draws using the libart package and 567freetype with near PostScript quality and functionality. It is currently 568the standard backend (as long as the required libraries are installed). 569@item w32 570This backend works on Windows and uses basic Windows drawing 571@item cairo 572An up-and-coming backend. It still relies on unpublished functions in 573the cairo library so using it is not for the beginner. 574@end table 575 576@c ------------------------- GNUstep GUI Library ----------------------- 577 578@node GNUstep DisplayGhostScript Server, , GNUstep GUI Library, Top 579@section GNUstep DisplayGhostScript Server 580 581@menu 582* What is the Display Ghostscript Server?:: 583* What is DGSs current state of development?:: 584* What is the relationship between the Display Ghostscript Server and X Windows?:: 585@end menu 586 587@node What is the Display Ghostscript Server?, What is DGSs current state of development?, GNUstep DisplayGhostScript Server, GNUstep DisplayGhostScript Server 588@subsection What is the Display Ghostscript Server? 589 590It is a free implementation of a Display PostScript server based on the 591GNU Ghostscript program developed by Aladdin Enterprises and now owned by artofcode LLC. 592 593At one point, GNUstep was using this for display purposes. However the 594development of DGS has stopped as it is too difficult to maintain and 595no one wanted to work on it. Now we are using other means of drawing. 596 597@node What is DGSs current state of development?, What is the relationship between the Display Ghostscript Server and X Windows?, What is the Display Ghostscript Server?, GNUstep DisplayGhostScript Server 598@subsection What is its current state of development? 599 600GNU contracted with Aladdin Enterprises to add some key features to GNU 601Ghostscript so it could be used as a DPS server. This work has mostly 602been done, although Aladdin did not completely finish the work that they 603were contracted for. (Because the work took longer than specified and 604was not completed, Aladdin agreed to waive approximately $10,000 in 605promised fees for the work that was actually done and delivered.) DGS 606works fairly well with a single context. Alpha channel and compositing 607doesn't work. 608 609Currently, further development on DGS has been abandoned. The library 610based approach using libart, cairo, etc works much better. 611 612@node What is the relationship between the Display Ghostscript Server and X Windows?, , What is DGSs current state of development?, GNUstep DisplayGhostScript Server 613@subsection What is the relationship between the Display Ghostscript Server and X Windows? 614 615Display Ghostscript runs on top of X Windows. 616 617@c ------------------ GNUstep DisplayGhostScript Server --------------- 618 619@bye 620\bye 621