Filter Arabic Letter Mark due to display corruption.

Under GNU Screen, the directional marker causes display corruption in
the index.

This (along with past filters added) should perhaps be considered GNU
Screen bugs.  They've been reported upstream a while ago, but so far
not received any attention.  So for Mutt users' benefit it's better to
filter them out for now.

Thanks to Vincent Lefèvre for debugging and reporting the problem,
along with providing historical information from similar past issues.

1 files changed, 2 insertions, 1 deletions

diff --git a/mbyte.c b/mbyte.c
index 5aa7fc40..16645feb 100644
--- a/mbyte.c
+++ b/mbyte.c
@@ -534,7 +534,8 @@ int is_display_corrupting_utf8 (wchar_t wc)
       (wc >= (wchar_t)0x2066 &&  /* misc directional markers */
        wc <= (wchar_t)0x2069) ||
       (wc >= (wchar_t)0x202a &&  /* misc directional markers: #3854 */
-       wc <= (wchar_t)0x202e))
+       wc <= (wchar_t)0x202e) ||
+      wc == (wchar_t)0x061c)     /* arabic letter mark: gitlab #413 */
     return 1;
   else
     return 0;