Bug 724554 - Don't exit fullscreen on window deactivate, just warn on refocus. r=dao

browser/base/content/browser-fullScreen.js

@@ -88,12 +88,10 @@ var FullScreen = {
 
   handleEvent: function (event) {
     switch (event.type) {
-      case "deactivate":
-        // We must call exitDomFullScreen asynchronously, since "deactivate" is
-        // dispatched in the middle of the focus manager's window lowering code,
-        // and the focus manager gets confused if we exit fullscreen mode in the
-        // middle of window lowering. See bug 729872.
-        setTimeout(this.exitDomFullScreen.bind(this), 0);
+      case "activate":
+        if (document.mozFullScreen) {
+          this.showWarning(this.fullscreenDoc);
+        }
         break;
       case "transitionend":
         if (event.propertyName == "opacity")
@@ -138,10 +136,11 @@ var FullScreen = {
     gBrowser.tabContainer.addEventListener("TabClose", this.exitDomFullScreen);
     gBrowser.tabContainer.addEventListener("TabSelect", this.exitDomFullScreen);
 
-    // Exit DOM full-screen mode when the browser window loses focus (ALT+TAB, etc).
-    if (!this.useLionFullScreen &&
-        gPrefService.getBoolPref("full-screen-api.exit-on-deactivate")) {
-      window.addEventListener("deactivate", this);
+    // Add listener to detect when the fullscreen window is re-focused.
+    // If a fullscreen window loses focus, we show a warning when the
+    // fullscreen window is refocused.
+    if (!this.useLionFullScreen) {
+      window.addEventListener("activate", this);
     }
 
     // Cancel any "hide the toolbar" animation which is in progress, and make
@@ -171,7 +170,8 @@ var FullScreen = {
       gBrowser.tabContainer.removeEventListener("TabClose", this.exitDomFullScreen);
       gBrowser.tabContainer.removeEventListener("TabSelect", this.exitDomFullScreen);
       if (!this.useLionFullScreen)
-        window.removeEventListener("deactivate", this);
+        window.removeEventListener("activate", this);
+      this.fullscreenDoc = null;
     }
   },
 
@@ -307,7 +307,6 @@ var FullScreen = {
   cancelWarning: function(event) {
     if (!this.warningBox)
       return;
-    this.fullscreenDoc = null;
     this.warningBox.removeEventListener("transitionend", this);
     if (this.warningFadeOutTimeout) {
       clearTimeout(this.warningFadeOutTimeout);

browser/base/content/browser.css

@@ -397,6 +397,14 @@ window[chromehidden~="toolbar"] toolbar:not(.toolbar-primary):not(.chromeclass-m
   opacity: 0.0;
 }
 
+/* When the modal fullscreen approval UI is showing, don't allow interaction
+   with the page, but when we're just showing the warning upon entering
+   fullscreen on an already approved page, do allow interaction with the page.
+ */
+#full-screen-warning-container:not([obscure-browser]) {
+  pointer-events: none;
+}
+
 #full-screen-warning-message {
   /* We must specify a max-width, otherwise word-wrap:break-word doesn't
      work in descendant <description> and <label> elements. Bug 630864. */

modules/libpref/src/init/all.js

@@ -3982,7 +3982,6 @@ pref("alerts.disableSlidingEffect", false);
 // DOM full-screen API.
 pref("full-screen-api.enabled", false);
 pref("full-screen-api.allow-trusted-requests-only", true);
-pref("full-screen-api.exit-on-deactivate", true);
 pref("full-screen-api.pointer-lock.enabled", true);
 
 // DOM idle observers API