Update >sequence docs

TODO.FACTOR.txt

@@ -23,6 +23,7 @@
 + ui:
 
 - support x11's large selections, if needed
+- own-selection violates ICCCM
 - one-column table doesn't need borders...?
 [2:45pm] tathi: Factor's text display is a bit odd sometimes, until you mouse over (or click, if there's no "live" text)
 [2:48pm] tathi: it appears to be using the font metrics from the sprite tuple, but re-using the texture from the previous letter

library/collections/sequence-combinators.facts

@@ -159,7 +159,7 @@ HELP: copy-into "( n dest src -- )"
 { $description "Copies all elements of " { $snippet "src" } " to " { $snippet "dest" } ", with destination indices starting from " { $snippet "n" } ". Grows " { $snippet "to" } " first if necessary." }
 { $errors "An error is thrown if " { $snippet "to" } " is not resizable, and not large enough to hold the copied elements." } ;
 
-HELP: >sequence "( seq quot -- )"
-{ $values { "seq" "a sequence" } { "quot" "a quotation with stack effect " { $snippet "( n -- newseq )" } } { "newseq" "a sequence" } }
-{ $description "Calls the quotation with the length of " { $snippet "seq" } ", creating a new sequence, and copies the contents of " { $snippet "seq" } " into the new sequence." }
+HELP: >sequence "( seq pred quot -- )"
+{ $values { "seq" "a sequence" } { "pred" "a quotation with stack effect " { $snippet "( seq -- ? )" } }{ "quot" "a quotation with stack effect " { $snippet "( n -- newseq )" } } { "newseq" "a freshly-allocated sequence" } }
+{ $description "If " { $snippet "pred" } " answers a true value given " { $snippet "seq" } ", clones " { $snippet "seq" } ". Otherwise, calls " { $snippet "quot" } " with the length of " { $snippet "seq" } ", creating a new sequence, and copies the contents of " { $snippet "seq" } " into the new sequence." }
 { $notes "This word is used to implement words which convert one type of sequence into another, for example " { $link >array } "." } ;