1 files changed, 11 insertions, 5 deletions
diff --git a/Master/texmf-dist/tex/context/base/strc-con.mkvi b/Master/texmf-dist/tex/context/base/strc-con.mkvi
index 3068fda0ba7..220de809a3b 100644
--- a/Master/texmf-dist/tex/context/base/strc-con.mkvi
+++ b/Master/texmf-dist/tex/context/base/strc-con.mkvi
@@ -233,6 +233,10 @@
    \constructionparameter\c!before
    \begingroup
    \edef\currentconstructionalternative{\constructionparameter\c!alternative}%
+ % \checkconstructionalternativeparent % this catches an unknown alternative
+   \doifnotsetups{\constructionalternativeparameter\c!renderingsetup}
+     {\letconstructionparameter\c!alternative\v!left
+      \let\currentconstructionalternative\v!left}%
    \doadaptleftskip{\constructionparameter\c!margin}%
    \setlocalhsize % so we can use \localhsize in width assignments
    \constructionsheaddistance\constructionalternativeparameter\c!distance\relax
@@ -257,9 +261,11 @@
    \setbox\constructionheadbox\hbox
      {\forgetall
       \dontcomplain
-      \doifelse{\constructionparameter\c!alternative}\v!serried % brrr, hack, will change
-        {\csname\??constructionmainhandler\currentconstructionhandler\endcsname\currentconstructiontext}
-        {\csname\??constructionmainhandler\currentconstructionhandler\endcsname{\boxedconstructionhead\currentconstructiontext}}}%
+      \ifx\currentconstructionalternative\v!serried % brrr, hack, will change
+        \csname\??constructionmainhandler\currentconstructionhandler\endcsname\currentconstructiontext
+      \else
+        \csname\??constructionmainhandler\currentconstructionhandler\endcsname{\boxedconstructionhead\currentconstructiontext}%
+      \fi}%
    \doifelse{\constructionparameter\c!aligntitle}\v!no
      {\leftconstructionskip \leftskip
       \rightconstructionskip\rightskip}
@@ -276,8 +282,8 @@
    \fi
    \strc_constructions_close_symbol_reset
    %
-   \doifnotsetups {\constructionalternativeparameter\c!renderingsetup}
-     {\let\currentconstructionalternative\v!left}%
+ % \doifnotsetups {\constructionalternativeparameter\c!renderingsetup}
+ %   {\let\currentconstructionalternative\v!left}%
    \directsetup{\constructionalternativeparameter\c!renderingsetup}\relax
    %
    \dostoptagged % tag