diff --git a/lib/ace/edit_session.js b/lib/ace/edit_session.js
index 36de153c..c022dd04 100644
--- a/lib/ace/edit_session.js
+++ b/lib/ace/edit_session.js
@@ -48,7 +48,7 @@ var Document = require("ace/document").Document;
 var NO_CHANGE_DELTAS = {};
 
 var EditSession = function(text, mode) {
-    this.modified = true;
+    this.$modified = true;
     this.selection = new Selection(this);
     this.$breakpoints = [];
 
@@ -294,7 +294,7 @@ var EditSession = function(text, mode) {
                 var len = lines[i].length;
                 longestLine = Math.max(longestLine, len);
 
-                lines[i].replace("\t", function(m) {
+                lines[i].replace(/\t/g, function(m) {
                     len += tabSize-1;
                     return m;
                 });
@@ -512,7 +512,7 @@ var EditSession = function(text, mode) {
     };
 
     this.indentRows = function(startRow, endRow, indentString) {
-        indentString = indentString.replace("\t", this.getTabString());
+        indentString = indentString.replace(/\t/g, this.getTabString());
         for (var row=startRow; row<=endRow; row++) {
             this.insert({row: row, column:0}, indentString);
         }
diff --git a/lib/ace/test/edit_session_test.js b/lib/ace/test/edit_session_test.js
index 4298df3a..c5f76b9b 100644
--- a/lib/ace/test/edit_session_test.js
+++ b/lib/ace/test/edit_session_test.js
@@ -242,6 +242,27 @@ var Test = {
         
         undoManager.redo();
         assert.equal(session.getValue(), ["1", "", "ad"].join("\n"));
+    },
+    
+    "test get longest line" : function() {
+        var session = new EditSession(["12"]);
+        session.setTabSize(4);
+        assert.equal(session.getWidth(), 2);
+        assert.equal(session.getScreenWidth(), 2);
+        
+        session.doc.insertNewLine(0);
+        session.doc.insertLines(1, ["123"]);
+        assert.equal(session.getWidth(), 3);
+        assert.equal(session.getScreenWidth(), 3);
+        
+        session.doc.insertNewLine(0);
+        session.doc.insertLines(1, ["\t\t"]);
+        assert.equal(session.getWidth(), 3);
+        assert.equal(session.getScreenWidth(), 8);
+        
+        session.setTabSize(2);
+        assert.equal(session.getWidth(), 3);
+        assert.equal(session.getScreenWidth(), 4);
     }
 };