tabular: add #:sep-properties

Also, correct the documentation about the interaction of
`#:sep` and property lists, and make the previous column's
properties used consistently for a separator column.

scribble-doc/scribblings/scribble/base.scrbl

@@ -261,7 +261,8 @@ Returns @racket[#t] if @racket[v] is an item produced by
                   [#:sep sep (or/c block? content? #f) #f]
                   [#:column-properties column-properties (listof any/c) '()]
                   [#:row-properties row-properties (listof any/c) '()]
-                  [#:cell-properties cell-properties (listof (listof any/c)) '()])
+                  [#:cell-properties cell-properties (listof (listof any/c)) '()]
+                  [#:sep-properties sep-properties (or/c list? #f) #f])
          table?]{
 
 Creates a @tech{table} with the given @racket[cells] content, which is
@@ -276,11 +277,11 @@ cell in a row.
 The @racket[style] argument is handled the same as @racket[para].
 See @racket[table] for a list of recognized @tech{style names} and @tech{style properties}.
 
-If @racket[sep] is not @racket[#f], it is inserted as a new column
+The default style places no space between table columns. If
-between every column in the table; note that any
+@racket[sep] is not @racket[#f], it is inserted as a new column
-@racket[table-columns] or @racket[table-cells] property in
+between every column in the table; the new column's properties are the
-@racket[style] must take the added columns into account. Otherwise,
+same as the preceding column's, unless @racket[sep-properties]
-the default style places no space between table columns. When @racket[sep]
+provides a list of @tech{style properties} to use. When @racket[sep]
 would be placed before a @racket['cont], a @racket['cont] is inserted,
 instead.
 
@@ -343,7 +344,10 @@ properties will be used from the merger into @racket[table-cells].}
                                @racket[#:row-properties],
                                and @racket[#:cell-properties] arguments.}
          #:changed "1.12" @elem{Changed @racket[sep] insertion before a
-                                @racket['cont].}]
+                                @racket['cont].}
+         #:changed "1.28" @elem{Added @racket[sep-properties] and made
+                                the preceding column's properties used
+                                consistently if not specified.}]
 
 Examples:
 @codeblock[#:keep-lang-line? #f]|{

scribble-lib/info.rkt

@@ -23,4 +23,4 @@
 
 (define pkg-authors '(mflatt eli))
 
-(define version "1.27")
+(define version "1.28")

scribble-lib/scribble/base.rkt

@@ -329,7 +329,8 @@
                 #:sep (or/c content? block? #f)
                 #:column-properties (listof any/c)
                 #:row-properties (listof any/c)
-                #:cell-properties (listof (listof any/c)))
+                #:cell-properties (listof (listof any/c))
+                #:sep-properties (or/c list? #f))
                table?)])
 
 (define (convert-block-style style)
@@ -352,6 +353,7 @@
 
 (define (tabular #:style [style #f]
                  #:sep [sep #f]
+                 #:sep-properties [sep-props #f]
                  #:column-properties [column-properties null]
                  #:row-properties [row-properties null]
                  #:cell-properties [cell-properties null]
@@ -426,7 +428,7 @@
                      [(null? column-properties)
                       (if (or (zero? n) (not sep))
                           (cons prev (loop null (add1 n) prev))
-                          (list* prev prev (loop null (+ n 2) prev)))]
+                          (list* (or sep-props prev) prev (loop null (+ n 2) prev)))]
                      [else
                       (define (to-list v) (if (list? v) v (list v)))
                       (define props (to-list (car column-properties)))
@@ -437,7 +439,7 @@
                                          props))
                       (if (or (zero? n) (not sep))
                           (cons props rest)
-                          (list* null props rest))])))
+                          (list* (or sep-props prev) props rest))])))
                 (define full-column-properties
                   (make-full-column-properties column-properties))
                 (define (make-full-cell-properties cell-properties)