Bug 1081542 - Part 7: Reflect middle click to window.open. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D201935

toolkit/components/windowwatcher/nsWindowWatcher.cpp

@@ -64,6 +64,7 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_middlemouse.h"
 #include "mozilla/StaticPrefs_full_screen_api.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/Storage.h"
@@ -2455,7 +2456,12 @@ bool nsWindowWatcher::IsWindowOpenLocationModified(
   bool metaKey = aModifiers.IsControl();
 #endif
   bool shiftKey = aModifiers.IsShift();
-  if (metaKey) {
+
+  bool middleMouse = aModifiers.IsMiddleMouse();
+  bool middleUsesTabs = StaticPrefs::browser_tabs_opentabfor_middleclick();
+  bool middleUsesNewWindow = StaticPrefs::middlemouse_openNewWindow();
+
+  if (metaKey || (middleMouse && middleUsesTabs)) {
     bool loadInBackground = StaticPrefs::browser_tabs_loadInBackground();
     if (shiftKey) {
       loadInBackground = !loadInBackground;
@@ -2467,11 +2473,18 @@ bool nsWindowWatcher::IsWindowOpenLocationModified(
     }
     return true;
   }
-  if (shiftKey) {
+
+  if (shiftKey || (middleMouse && !middleUsesTabs && middleUsesNewWindow)) {
     *aLocation = nsIBrowserDOMWindow::OPEN_NEWWINDOW;
     return true;
   }
 
+  // If both middleUsesTabs and middleUsesNewWindow are false, it means the
+  // middle-click is used for different purpose, such as paste or scroll.
+  // Webpage still can trigger `window.open` for the user activation, and in
+  // that case use the `window.open`'s `features` parameter and other prefs to
+  // decide where to open.
+
   return false;
 }
 

toolkit/content/tests/browser/browser_cancel_starting_autoscrolling_requested_by_background_tab.js

@@ -13,6 +13,7 @@ add_task(async function testStopStartingAutoScroll() {
         "accessibility.mouse_focuses_formcontrol",
         !navigator.platform.includes("Mac"),
       ],
+      ["browser.tabs.loadInBackground", false],
     ],
   });