Update developer_manual/compatibility.rst

developer_manual/compatibility.rst

@@ -1,4 +1,39 @@
 Compatibility Notes
 ===================
 
-See http://owncloud.org/dev/apps/make-owncloud-3-apps-compatible-with-owncloud-4/
+See http://owncloud.org/dev/apps/make-owncloud-3-apps-compatible-with-owncloud-4/
+
+**THIS NEEDS FORMATTED**
+
+One of our major improvements of ownCloud 4 are movable apps. Therefore we changed the way ownCloud loads apps. Apps used to be called directly through their index.php (e.g.: /files/index.php). The problem has been that apps would not been movable if they contain a hardcoded link to the Base Library.
+Apps will be called trough an parameter in ownCloud 4. An example for this is: /?app=files.
+ownCloud 3 apps are not supported regarding to this mayor change, but making an ownCloud 3 app compatible with ownCloud 4 is pretty easy.
+The first step is to remove the require_once command to the Base library in every file of your app.
+Afterwords you have to make sure that your app uses the ownCloud internal functions to generate paths.
+Paths:
+
+For generating a path in PHP use our new public API:
+
+OCP\Util::linkTo
+
+and for generating a path in Js use the function:
+
+OC.filePath
+
+CSS:
+
+You have to use the placeholders %appswebroot% and %webroot%, if your CSS file contains relative paths.
+
+Example from our source code:
+
+#contacts_deletecard {position:relative; float:left; background:url('%webroot%/core/img/actions/delete.svg') no-repeat center; }
+
+public.php and remote.php
+
+We introduced the files public.php and remote.php in ownCloud 4.
+
+If you want to know how to use them, you should take a look here.
+
+New public API
+
+We also introduced our new public api. The documentation for this api can be found at api.ownCloud.org.