diff --git a/js/dialog.js b/js/dialog.js
index 3fd7a95..a84819e 100644
--- a/js/dialog.js
+++ b/js/dialog.js
@@ -1,4 +1,4 @@
-define(["dom2"], function() {
+define(["editor", "dom2"], function(editor) {
 
   return function(text, buttons, callback) {
     if (typeof buttons == "function" || typeof buttons == "undefined") {
@@ -30,6 +30,7 @@ define(["dom2"], function() {
       modal.remove();
       var value = JSON.parse(this.value);
       if (callback) callback(value);
+      editor.focus();
     };
 
     buttons.forEach(function(options) {
@@ -42,13 +43,18 @@ define(["dom2"], function() {
       }
       button.innerHTML = options.label;
       button.value = options.value;
+      if (options.focus) {
+        button.className = "default";
+      }
       buttonRow.append(button);
       button.on("click", clickButton);
     });
 
     setTimeout(function() {
       //ensure focus, even from palette (which normally refocuses editor)
-      modal.find("button").focus();
+      var button = modal.find("button.default");
+      if (!button) button = modal.find("button");
+      button.focus();
     });
 
   }
diff --git a/js/fileManager.js b/js/fileManager.js
index 9198925..5f2ea3f 100644
--- a/js/fileManager.js
+++ b/js/fileManager.js
@@ -53,6 +53,29 @@ define([
       sessions.renderTabs();
     });
   });
+  command.on("session:check-file", function() {
+    var tab = sessions.getCurrent();
+    if (!tab.file) return;
+    tab.file.entry.file(function(entry) {
+      if (tab.modifiedAt && entry.lastModifiedDate > tab.modifiedAt) {
+        if (tab.modified) {
+          dialog(
+            "This file has been modified since the last time it was saved. Would you like to reload?",
+            [{label: "Reload", value: true}, {label: "Cancel", value: false, focus: true}],
+            function(confirmed) {
+              if (confirmed) {
+                command.fire("session:revert-file");
+              } else {
+                tab.modifiedAt = new Date();
+              }
+            }
+          );
+        } else {
+          command.fire("session:revert-file");
+        }
+      }
+    });
+  });
   
   command.on("session:open-settings-file", function(name) {
     Settings.load(name, function() {
diff --git a/js/sessions.js b/js/sessions.js
index e1fd53c..3dd9075 100644
--- a/js/sessions.js
+++ b/js/sessions.js
@@ -19,6 +19,7 @@ define([
     if (file) {
       session.file = file;
       session.fileName = file.entry.name;
+      session.modifiedAt = new Date();
     } else {
       session.fileName = "untitled.txt";
     }
@@ -46,6 +47,7 @@ define([
       var whenOpen = function() {
         self.file.write(content, c);
         self.modified = false;
+        self.modifiedAt = new Date();
         renderTabs();
       };
 
@@ -233,6 +235,7 @@ define([
   var raiseTab = function(index) {
     var tab = tabs[index];
     tab.raise();
+    command.fire("session:check-file");
   };
   
   var switchTab = function(shift) {