{"id":7959,"date":"2016-10-13T15:52:10","date_gmt":"2016-10-13T22:52:10","guid":{"rendered":"http:\/\/blog.mozilla.org\/addons\/?p=7959"},"modified":"2016-10-14T14:07:45","modified_gmt":"2016-10-14T21:07:45","slug":"compatibility-for-firefox-51","status":"publish","type":"post","link":"https:\/\/blog.mozilla.org\/addons\/2016\/10\/13\/compatibility-for-firefox-51\/","title":{"rendered":"Add-on Compatibility for Firefox 51"},"content":{"rendered":"<p>Firefox 51 will be <a href=\"https:\/\/wiki.mozilla.org\/RapidRelease\/Calendar\">released<\/a> on January 24th. Note that the scheduled release on December 13th is a point release, not a major release, hence the much longer cycle. Here&#8217;s the list of changes that went into this version that can affect add-on compatibility. There is more information available in <a href=\"https:\/\/developer.mozilla.org\/en-US\/Firefox\/Releases\/51\">Firefox 51 for Developers<\/a>, so you should also give it a look.<\/p>\n<h3>General<\/h3>\n<ul>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=528005\">Let accel-click and middle-click on the new tab button open a new tab next to the current one<\/a>. This changes the behavior of the new tab button and removes the <code>BrowserOpenNewTabOrWindow<\/code> function.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=1167575\">Code executed in wrong order with <code>setTimeout<\/code> after alert<\/a>. This changes the behavior of the <code>onButtonClick<\/code> function to make it async.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=812701\">Drop the prefixed version of visibility API<\/a>. This removes <code>mozVisibilityState<\/code> and <code>mozHidden<\/code>.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=790919\">Don&#8217;t dispatch close event, and remove onclose<\/a>. This applies to Workers.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=1298923\">Prevent installation of an extension when &#8220;*&#8221; is used as part of <code>strict_min_version<\/code> in a WebExtension <code>manifest.json<\/code>)<\/a>. Minimum versions should always be specific versions, rather than a mask.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=289714\">Loaded-as-data XML documents should not generate <code>&lt;parsererror&gt;<\/code><\/a>. Some add-ons are relying on this node showing up if an XML document fails to parse.<\/li>\n<\/ul>\n<h3>XPCOM and Modules<\/h3>\n<ul>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=1227289\"><code><\/code>Default to the NullPrincipal rather than SystemPrincipal for Favicons<\/a>. This changes the functions <code>setAndFetchFaviconForPage<\/code> and <code>replaceFaviconDataFromDataURL<\/code>. The principal should generally be passed as an argument.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=306471\">Upload setting wrong Content-Type for files if you downloaded from a server that provided the wrong Content-Type<\/a>. As explained in <a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=306471#c36\">comment #36<\/a>, the way add-ons change the MIME type mappings is now different, via a category rather than directly changing <code>mimeTypes.rdf<\/code>.<\/li>\n<li><a href=\"https:\/\/bugzilla.mozilla.org\/show_bug.cgi?id=1288423\">Remove the last references to <code>Actor<\/code>\/<code>FrontClass<\/code><\/a>. While both of these still work for add-ons, they should be considered as deprecated.<\/li>\n<\/ul>\n<h3>New!<\/h3>\n<ul>\n<li><a href=\"https:\/\/developer.mozilla.org\/en-US\/Add-ons\/WebExtensions\/Embedded_WebExtensions\">Embedded WebExtensions<\/a>. You can now embed a WebExtension into any restartless add-on, allowing you to gradually migrate your code to the new platform, or transition any data you store to a format that works with WebExtensions.<\/li>\n<li><a href=\"https:\/\/webextensions-experiments.readthedocs.io\/en\/latest\/index.html\">WebExtension Experiments<\/a>. This is a mechanism that allows us (and you!) to prototype new WebExtensions APIs.<\/li>\n<\/ul>\n<p>Let me know in the comments if there&#8217;s anything missing or incorrect on these lists. If your add-on breaks on Firefox 51, I&#8217;d like to know.<\/p>\n<p>The automatic compatibility validation and upgrade for add-ons on AMO will happen in a few weeks, so keep an eye on your email if you have an add-on listed on our site with its compatibility set to Firefox 50.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Firefox 51 will be released on January 24th. Note that the scheduled release on December 13th is a point release, not a major release, hence the much longer cycle. Here&#8217;s &hellip; <a class=\"go\" href=\"https:\/\/blog.mozilla.org\/addons\/2016\/10\/13\/compatibility-for-firefox-51\/\">Read more<\/a><\/p>\n","protected":false},"author":173,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[388,44,295],"tags":[278877,278873,278876,288918,278871],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Add-on Compatibility for Firefox 51 - Mozilla Add-ons Community Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.mozilla.org\/addons\/2016\/10\/13\/compatibility-for-firefox-51\/\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Jorge Villalobos\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/blog.mozilla.org\/addons\/2016\/10\/13\/compatibility-for-firefox-51\/\",\"url\":\"https:\/\/blog.mozilla.org\/addons\/2016\/10\/13\/compatibility-for-firefox-51\/\",\"name\":\"Add-on Compatibility for Firefox 51 - 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