Fixed: after ":ownsyntax perl" and ":e" syntax was cleared in other window.

runtime/doc/todo.txt

@@ -1085,9 +1085,14 @@ restored. (Luc St-Louis)
 
 Vim 7.3:
 - Included conceal patch.
+    HL disappears in other window:
+	:sp
+	:ownsyntax perl
+	:e
+    Documentation update:
 	remove w:ownsyntax, automatically set w:current_syntax to the value of
-    b:current_syntax after loading a syntax file.
-    :ownsyntax only sets w:current_syntax.
+	b:current_syntax after loading a syntax file.  :ownsyntax only sets
+	w:current_syntax.
 - using NSIS 2.46: install on Windows 7 works, but no "Edit with Vim" menu.
    Use register_shell_extension()? (George Reilly, 2010 May 26)
    Ron's version: http://dev.ronware.org/p/vim/finfo?name=gvim.nsi

src/buffer.c

@@ -1379,12 +1379,7 @@ enter_buffer(buf)
 #endif
 
 #ifdef FEAT_SYN_HL
-    if (curwin->w_s != &curwin->w_buffer->b_s)
-    {
-	/* Get rid of independant syntax */
-	syntax_clear(curwin->w_s);
-	vim_free(curwin->w_s);
-    }
+    reset_synblock(curwin);
     curwin->w_s = &(buf->b_s);
 #endif
     /* Get the buffer in the current window. */

src/ex_cmds.c

@@ -3571,6 +3571,9 @@ do_ecmd(fnum, ffname, sfname, eap, newlnum, flags, oldwin)
 	    new_name = NULL;
 #endif
 	buf_freeall(curbuf, FALSE, FALSE);   /* free all things for buffer */
+#ifdef FEAT_SYN_HL
+	reset_synblock(curwin);	    /* remove any ownsyntax */
+#endif
 #ifdef FEAT_AUTOCMD
 	/* If autocommands deleted the buffer we were going to re-edit, give
 	 * up and jump to the end. */

src/proto/syntax.pro

@@ -6,6 +6,7 @@ void syntax_end_parsing __ARGS((linenr_T lnum));
 int syntax_check_changed __ARGS((linenr_T lnum));
 int get_syntax_attr __ARGS((colnr_T col, int *p_flags, int *can_spell, int keep_state));
 void syntax_clear __ARGS((synblock_T *block));
+void reset_synblock __ARGS((win_T *wp));
 void ex_syntax __ARGS((exarg_T *eap));
 void ex_ownsyntax __ARGS((exarg_T *eap));
 int syntax_present __ARGS((win_T *win));

src/syntax.c

@@ -3420,6 +3420,21 @@ syntax_clear(block)
     invalidate_current_state();
 }
 
+/*
+ * Get rid of ownsyntax for window "wp".
+ */
+    void
+reset_synblock(wp)
+    win_T *wp;
+{
+    if (wp->w_s != &wp->w_buffer->b_s)
+    {
+	syntax_clear(wp->w_s);
+	vim_free(wp->w_s);
+	wp->w_s = &wp->w_buffer->b_s;
+    }
+}
+
 /*
  * Clear syncing info for one buffer.
  */
@@ -3538,7 +3553,6 @@ syn_cmd_clear(eap, syncing)
 	    if (curwin->w_s == &curwin->w_buffer->b_s)
 		do_unlet((char_u *)"b:current_syntax", TRUE);
 	    do_unlet((char_u *)"w:current_syntax", TRUE);
-
 	}
     }
     else

src/window.c

@@ -1176,7 +1176,8 @@ win_init(newp, oldp, flags)
 
     newp->w_buffer = oldp->w_buffer;
 #ifdef FEAT_SYN_HL
-    newp->w_s = oldp->w_s;
+    /* TODO: use reference count? */
+    newp->w_s = &(oldp->w_buffer->b_s);
 #endif
     oldp->w_buffer->b_nwindows++;
     newp->w_cursor = oldp->w_cursor;
@@ -4408,12 +4409,7 @@ win_free(wp, tp)
 #endif /* FEAT_GUI */
 
 #ifdef FEAT_SYN_HL
-    /* free independent synblock */
-    if (wp->w_s != &wp->w_buffer->b_s)
-    {
-	syntax_clear(wp->w_s);
-	vim_free(wp->w_s);
-    }
+    reset_synblock(wp);  /* free independent synblock */
 #endif
 
 #ifdef FEAT_AUTOCMD