From 16a3baa743a14c0422a577a86d2be305de3514c3 Mon Sep 17 00:00:00 2001
From: Jonathan Kew <jkew@mozilla.com>
Date: Fri, 26 Apr 2013 12:41:29 +0100
Subject: [PATCH] bug 864107 - constrain restored window dimensions to
 available screen area. r=ttaubert

---
 .../sessionstore/src/SessionStore.jsm         | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/browser/components/sessionstore/src/SessionStore.jsm b/browser/components/sessionstore/src/SessionStore.jsm
index 793ab128607..1257cf274fb 100644
--- a/browser/components/sessionstore/src/SessionStore.jsm
+++ b/browser/components/sessionstore/src/SessionStore.jsm
@@ -83,6 +83,8 @@ Cu.import("resource://gre/modules/commonjs/sdk/core/promise.js", this);
 
 XPCOMUtils.defineLazyServiceGetter(this, "gSessionStartup",
   "@mozilla.org/browser/sessionstartup;1", "nsISessionStartup");
+XPCOMUtils.defineLazyServiceGetter(this, "gScreenManager",
+  "@mozilla.org/gfx/screenmanager;1", "nsIScreenManager");
 
 // List of docShell capabilities to (re)store. These are automatically
 // retrieved from a given docShell if not already collected before.
@@ -3579,6 +3581,31 @@ let SessionStoreInternal = {
     var _this = this;
     function win_(aName) { return _this._getWindowDimension(win, aName); }
 
+    // find available space on the screen where this window is being placed
+    let screen = gScreenManager.screenForRect(aLeft, aTop, aWidth, aHeight);
+    if (screen) {
+      let screenLeft = {}, screenTop = {}, screenWidth = {}, screenHeight = {};
+      screen.GetAvailRectDisplayPix(screenLeft, screenTop, screenWidth, screenHeight);
+      // constrain the dimensions to the actual space available
+      if (aWidth > screenWidth.value) {
+        aWidth = screenWidth.value;
+      }
+      if (aHeight > screenHeight.value) {
+        aHeight = screenHeight.value;
+      }
+      // and then pull the window within the screen's bounds
+      if (aLeft < screenLeft.value) {
+        aLeft = screenLeft.value;
+      } else if (aLeft + aWidth > screenLeft.value + screenWidth.value) {
+        aLeft = screenLeft.value + screenWidth.value - aWidth;
+      }
+      if (aTop < screenTop.value) {
+        aTop = screenTop.value;
+      } else if (aTop + aHeight > screenTop.value + screenHeight.value) {
+        aTop = screenTop.value + screenHeight.value - aHeight;
+      }
+    }
+
     // only modify those aspects which aren't correct yet
     if (aWidth && aHeight && (aWidth != win_("width") || aHeight != win_("height"))) {
       aWindow.resizeTo(aWidth, aHeight);