From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Michael Welsh Duggan Newsgroups: gmane.emacs.devel Subject: Re: Display question Date: Wed, 08 Jun 2011 09:13:20 -0400 Message-ID: <87boy8h3f3.fsf@maru.md5i.com> References: <87hb80hno5.fsf@maru.md5i.com> <8339jkdam3.fsf@gnu.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1307538916 21468 80.91.229.12 (8 Jun 2011 13:15:16 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 8 Jun 2011 13:15:16 +0000 (UTC) Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Jun 08 15:15:12 2011 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([140.186.70.17]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1QUIbH-0007L9-Q4 for ged-emacs-devel@m.gmane.org; Wed, 08 Jun 2011 15:15:11 +0200 Original-Received: from localhost ([::1]:53573 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QUIbG-0007f0-F5 for ged-emacs-devel@m.gmane.org; Wed, 08 Jun 2011 09:15:10 -0400 Original-Received: from eggs.gnu.org ([140.186.70.92]:41332) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QUIZZ-0007Mu-Ok for emacs-devel@gnu.org; Wed, 08 Jun 2011 09:13:28 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QUIZY-0002FC-3q for emacs-devel@gnu.org; Wed, 08 Jun 2011 09:13:25 -0400 Original-Received: from md5i.com ([75.151.244.229]:53217 helo=maru.md5i.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QUIZV-0002EW-Gb; Wed, 08 Jun 2011 09:13:21 -0400 Original-Received: from md5i by maru.md5i.com with local (Exim 4.76) (envelope-from ) id 1QUIZU-00087W-BS; Wed, 08 Jun 2011 09:13:20 -0400 In-Reply-To: <8339jkdam3.fsf@gnu.org> (Eli Zaretskii's message of "Wed, 08 Jun 2011 10:51:32 +0300") User-Agent: Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 75.151.244.229 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:140298 Archived-At: Eli Zaretskii writes: >> From: Michael Welsh Duggan >> Date: Wed, 08 Jun 2011 01:55:54 -0400 >> >> Afterward, I get a character that looks like a double-boxed RLO. Image >> included: >> >> Is this expected? If I just do (insert RLO RLO RLO) a few times in a >> non-font-locked buffer, I get a box around RLO, with a tiny space >> between the boxes, and not the double box seen here. > > The difference between these two use cases is that characters > delivered from display tables are not subject to the treatment we give > to "glyphless characters", which is what u+200b ZERO WIDTH SPACE is. > You expect this character to be displayed as a thin space (probably to > get the boxed "RLO" look prettier), but this thin space will only show > when u+200b is treated as a glyphless character, which can happen when > it comes from the buffer, but not from a display table. [...] > Btw, you cannot expect that u+200b is displayed as a thin space, > because the user could change that via glyphless-char-display-control, > which see. So this particular use of u+200b is questionable to begin > with, IMO. I wasn't actually thinking it would appear as a space when I initially tried it. I was using it to separate two runs of character properties so the boxes wouldn't join if they were next to each other. (This does and does not work if I set u+200b to zero-width. I think this confuses the display mechanism a little.) I did not know about glyphless-char-display, which seems to have the feature I was trying to implement built in. Thanks for the help. (I was playing around with ideas on how to display and undisplay bidi control characters, as you might have guessed.) -- Michael Welsh Duggan (md5i@md5i.com)