split unstable docs into non-gui and gui

This split fixes a broken test for whether to include the gui
documentation, which in turn exposes documentation dependencies,
which means that the dependencies are wrong again at this point.

pkgs/unstable/info.rkt

@@ -3,7 +3,8 @@
 (define collection "unstable")
 
 (define scribblings
-  '(("scribblings/unstable.scrbl" (multi-page) (experimental))))
+  '(("scribblings/unstable.scrbl" (multi-page) (experimental))
+    ("scribblings/gui/unstable-gui.scrbl" (multi-page) (experimental))))
 (define deps '("base"
                "draw-lib"
                "gui-lib"

pkgs/unstable/scribblings/gui.scrbl

@@ -1,17 +0,0 @@
-#lang scribble/doc
-@(require scribble/base
-          scribble/manual
-          (for-label scribble/base))
-
-@title[#:style '(toc) #:tag "unstable-gui"]{GUI Libraries}
-
-@local-table-of-contents[#:style 'immediate-only]
-
-@include-section["gui/notify.scrbl"]
-@include-section["gui/prefs.scrbl"]
-@include-section["gui/pict.scrbl"]
-@include-section["gui/slideshow.scrbl"]
-@include-section["gui/pslide.scrbl"]
-@include-section["gui/redex.scrbl"]
-@include-section["gui/snip.scrbl"]
-@include-section["gui/scribble.scrbl"]

pkgs/unstable/scribblings/gui/unstable-gui.scrbl

@@ -0,0 +1,22 @@
+#lang scribble/doc
+@(require scribble/base
+          scribble/manual
+          (for-label scribble/base))
+
+@title[#:style '(toc) #:tag "unstable-gui"]{Unstable GUI: May Change Without Warning}
+
+This manual documents GUI libraries available in the
+@racketidfont{unstable} collection. See @other-doc['(lib
+"unstable/scribblings/unstable.scrbl")] for more information about
+unstable libraries.
+
+@local-table-of-contents[#:style 'immediate-only]
+
+@include-section["notify.scrbl"]
+@include-section["prefs.scrbl"]
+@include-section["pict.scrbl"]
+@include-section["slideshow.scrbl"]
+@include-section["pslide.scrbl"]
+@include-section["redex.scrbl"]
+@include-section["snip.scrbl"]
+@include-section["scribble.scrbl"]

pkgs/unstable/scribblings/unstable.scrbl

@@ -7,7 +7,9 @@
 @title[#:tag "unstable"]{Unstable: May Change Without Warning}
 
 This manual documents some of the libraries available in the
-@racketidfont{unstable} collection.
+@racketidfont{unstable} collection. See also @other-doc['(lib
+"unstable/scribblings/gui/unstable-gui.scrbl") #:indirect "unstable
+GUI libraries"].
 
 The name @racketidfont{unstable} is intended as a warning that the
 @bold{interfaces} in particular are unstable. Developers of planet
@@ -107,25 +109,3 @@ Keep documentation and tests up to date.
 @include-section["../temp-c/scribblings/temp-c.scrbl"]
 @include-section["socket.scrbl"] ;; Unix Domain Sockets
 @include-section["2d.scrbl"]
-
-@;{--------}
-
-@;{
-  Include the "Unstable GUI libraries docs" if it is part of
-  the current distribution.
-}
-
-@(begin
-   ;; Include gui.scrbl if present.
-   (define-for-syntax here
-     (build-path (collection-path "unstable") "scribblings"))
-   (define-for-syntax gui-file
-     "gui.scrbl")
-   (define-syntax (if-gui-present stx)
-     (syntax-case stx ()
-       [(_ then else)
-        (if (file-exists? (build-path here gui-file))
-            #'then
-            #'else)])))
-
-@if-gui-present[(include-section "gui.scrbl") (begin)]

pkgs/unstable/scribblings/utils.rkt

@@ -17,7 +17,8 @@ Place either @unstable or @unstable-header immediately after the
 (define (unstable-header)
   @para{This library is @emph{unstable};
         compatibility will not be maintained.
-        See @secref{unstable} for more information.})
+        See @secref["unstable" #:doc '(lib "unstable/scribblings/unstable.scrbl")]
+        for more information.})
 
 (define (addition name)
   @margin-note{The subsequent bindings were added by @|name|.})