this fixes #1022

src/js/1p-filters.js

@@ -143,17 +143,22 @@ var exportUserFiltersToFile = function() {
 /******************************************************************************/
 
 var applyChanges = function() {
+    var textarea = uDom.nodeFromId('userFilters');
+
     var onWritten = function(details) {
         if ( details.error ) {
             return;
         }
+        textarea.value = details.content;
         cachedUserFilters = details.content.trim();
         userFiltersChanged();
         allFiltersApplyHandler();
+        textarea.focus();
     };
+
     var request = {
         what: 'writeUserFilters',
-        content: uDom('#userFilters').val()
+        content: textarea.value
     };
     messager.send(request, onWritten);
 };

src/js/messaging.js

@@ -862,10 +862,10 @@ var onMessage = function(request, sender, callback) {
     // Async
     switch ( request.what ) {
     case 'readUserFilters':
-        return µb.assets.get(µb.userFiltersPath, callback);
+        return µb.loadUserFilters(callback);
 
     case 'writeUserFilters':
-        return µb.assets.put(µb.userFiltersPath, request.content, callback);
+        return µb.saveUserFilters(request.content, callback);
 
     default:
         break;

src/js/storage.js

@@ -151,6 +151,12 @@
 /******************************************************************************/
 
 µBlock.saveUserFilters = function(content, callback) {
+    // https://github.com/gorhill/uBlock/issues/1022
+    // Be sure to end with an empty line.
+    content = content.trim();
+    if ( content !== '' ) {
+        content += '\n';
+    }
     this.assets.put(this.userFiltersPath, content, callback);
 };