There are several parts to this: * Behaving correctly when the system locale changes to an RTL locale. This *should* just work. * Behaving correctly when the system locale is RTL, and a LTR locale is picked in the locale switcher. * ... LTR -> RTL. * And allowing all of this at runtime. Marking this as a meta bug of its very own.

Here are some useful tips working with RTL (i18n in Trello) http://fragmentedpodcast.com/episodes/049/ and (RTL support in Facebook) https://www.youtube.com/watch?v=4dJHtT4-vBE I'll come up some action items later

No luck after following this https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Configuring_Build_Options#Localization. below is my mozconfig ( ar and ara) won't work either ======================================================== mk_add_options MOZ_CO_LOCALES=ar ac_add_options --enable-ui-locale=ar ac_add_options --with-l10n-base=/Users/nechen/objdir-l10n And here's the error message from ./mach. And strings.xml (en) is also missing ======================================================== 1:32.85 make[6]: *** [default] Error 2 1:32.85 make[5]: *** [.locales.deps] Error 2 1:32.85 make[5]: *** Deleting file `.locales.deps' 1:32.85 make[5]: *** Waiting for unfinished jobs.... 1:34.34 Note: Some input files use or override a deprecated API. 1:34.34 Note: Recompile with -Xlint:deprecation for details. 1:37.06 Note: Some input files use or override a deprecated API. 1:37.06 Note: Recompile with -Xlint:deprecation for details. 1:37.06 Note: Some input files use unchecked or unsafe operations. 1:37.06 Note: Recompile with -Xlint:unchecked for details. 1:37.34 make[4]: *** [mobile/android/base/libs] Error 2 1:37.34 make[3]: *** [libs] Error 2 1:37.34 make[2]: *** [default] Error 2 1:37.34 make[1]: *** [realbuild] Error 2 1:37.34 make: *** [build] Error 2 1:37.37 0 compiler warnings present. Is there any updated document about localization build? Thanks!

(In reply to Nevin Chen [:nechen] from comment #2) > Is there any updated document about localization build? Thanks! ahunt has been doing those kinds of builds in the past and is looking into updating the docs accordingly now. In the meantime, if you just want to test UI related things, maybe Android's developer setting for forcing RTL layout direction is helpful.

Hi Ioana and Sorina , would you please help us verify this RTL support on Fennec after Bug 1319302 is already resolved fixed ? Besides, Could you help us create the complete RTL test cases and its corresponding wiki test page for tracking ? Or did you already have the wiki page for RTL test plan on Fennec ? Thank you very much !

Installing an Arabic build works fine with an Arabic system as well. Can’t test other scenarios as I can’t seem to find a multi-locale build of nightly.

Hi Sorina, Do we get any chances to test the Locale switching functionality at your side ? or is it impossible ? Thank you very much for your support!

Hi Rachelle, sorry for delay here. I will test and put the results here, soon. Thank you!

Devices: - Nexus 9 (Android 7.0) - Nexus 5 (Android 6.0.1) - LG G4 (Android 5.1) Build: - Nightly (2017-01-04) - AR with Arabic system language and FA with Persian system language. Scenarios: 1. Opening multiple tabs and leave Nightly in background, switching between apps, including Chrome, Firefox Beta, Firefox Aurora, Facebook app. 2. Opening external links in all branches, then back to Nightly. Close - reopen Nightly. 3. Search Activity widget. In all the cases Nightly performed well, no delays in opening the pages, no changes from RTL to LTR. Please let me know if I missed something. Thanks!

(In reply to Khaled Hosny from comment #5) > Installing an Arabic build works fine with an Arabic system as well. Can’t > test other scenarios as I can’t seem to find a multi-locale build of nightly. Here you can find the multi builds - if you wanna investigate in the future. http://ftp.mozilla.org/pub/mobile/nightly/latest-mozilla-central-android-api-15/ Based on Sorina's comment and my investigations today I see no issues at this. Only concerning things is the BiDi in Top sites/ History that for a LTR is a bit confusing 9 discussed with L10n people and it seems it is k ) Fennec AR and Multi 53.0a1 2017-01-18