--- a/devtools/client/framework/devtools-browser.js
+++ b/devtools/client/framework/devtools-browser.js
@@ -223,72 +223,77 @@ var gDevToolsBrowser = exports.gDevTools
     let win = Services.wm.getMostRecentWindow("devtools:webide");
     if (win) {
       win.focus();
     } else {
       Services.ww.openWindow(null, "chrome://webide/content/", "webide", "chrome,centerscreen,resizable", null);
     }
   },
 
-  _getContentProcessTarget: function () {
+  _getContentProcessTarget: function (processId) {
     // Create a DebuggerServer in order to connect locally to it
     if (!DebuggerServer.initialized) {
       DebuggerServer.init();
       DebuggerServer.addBrowserActors();
     }
     DebuggerServer.allowChromeProcess = true;
 
     let transport = DebuggerServer.connectPipe();
     let client = new DebuggerClient(transport);
 
     let deferred = defer();
     client.connect().then(() => {
-      client.mainRoot.listProcesses(response => {
-        // Do nothing if there is only one process, the parent process.
-        let contentProcesses = response.processes.filter(p => (!p.parent));
-        if (contentProcesses.length < 1) {
-          let msg = L10N.getStr("toolbox.noContentProcess.message");
-          Services.prompt.alert(null, "", msg);
-          deferred.reject("No content processes available.");
-          return;
-        }
-        // Otherwise, arbitrary connect to the unique content process.
-        client.getProcess(contentProcesses[0].id)
-              .then(response => {
-                let options = {
-                  form: response.form,
-                  client: client,
-                  chrome: true,
-                  isTabActor: false
-                };
-                return TargetFactory.forRemoteTab(options);
-              })
-              .then(target => {
-                // Ensure closing the connection in order to cleanup
-                // the debugger client and also the server created in the
-                // content process
-                target.on("close", () => {
-                  client.close();
-                });
-                deferred.resolve(target);
+      client.getProcess(processId)
+            .then(response => {
+              let options = {
+                form: response.form,
+                client: client,
+                chrome: true,
+                isTabActor: false
+              };
+              return TargetFactory.forRemoteTab(options);
+            })
+            .then(target => {
+              // Ensure closing the connection in order to cleanup
+              // the debugger client and also the server created in the
+              // content process
+              target.on("close", () => {
+                client.close();
               });
-      });
+              deferred.resolve(target);
+            });
     });
 
     return deferred.promise;
   },
 
-   // Used by browser-sets.inc, command
-  openContentProcessToolbox: function () {
-    this._getContentProcessTarget()
-        .then(target => {
-          // Display a new toolbox, in a new window, with debugger by default
-          return gDevTools.showToolbox(target, "jsdebugger",
-                                       Toolbox.HostType.WINDOW);
-        });
+   // Used by menus.js
+  openContentProcessToolbox: function (gBrowser) {
+    let { childCount } = Services.ppmm;
+    // Get the process message manager for the current tab
+    let mm = gBrowser.selectedBrowser.messageManager.processMessageManager;
+    let processId = null;
+    for (let i = 1; i < childCount; i++) {
+      let child = Services.ppmm.getChildAt(i);
+      if (child == mm) {
+        processId = i;
+        break;
+      }
+    }
+    if (processId) {
+      this._getContentProcessTarget(processId)
+          .then(target => {
+            // Display a new toolbox, in a new window, with debugger by default
+            return gDevTools.showToolbox(target, "jsdebugger",
+                                         Toolbox.HostType.WINDOW);
+          });
+    } else {
+      let msg = L10N.getStr("toolbox.noContentProcessForTab.message");
+      Services.prompt.alert(null, "", msg);
+    }
   },
 
   /**
    * Install Developer widget
    */
   installDeveloperWidget: function () {
     let id = "developer-button";
     let widget = CustomizableUI.getWidget(id);

--- a/devtools/client/locales/en-US/toolbox.properties
+++ b/devtools/client/locales/en-US/toolbox.properties
@@ -88,20 +88,20 @@ browserConsoleCmd.commandkey=j
 # This is the tooltip of the pick button in the toolbox toolbar
 pickButton.tooltip=Pick an element from the page
 
 # LOCALIZATION NOTE (sidebar.showAllTabs.tooltip)
 # This is the tooltip shown when hover over the '…' button in the tabbed side
 # bar, when there's no enough space to show all tabs at once
 sidebar.showAllTabs.tooltip=All tabs
 
-# LOCALIZATION NOTE (toolbox.noContentProcess.message)
+# LOCALIZATION NOTE (toolbox.noContentProcessForTab.message)
 # Used as a message in the alert displayed when trying to open a browser
-# content toolbox and there is no content process running
-toolbox.noContentProcess.message=No content process running.
+# content toolbox and there is no content process running for the current tab
+toolbox.noContentProcessForTab.message=No content process for this tab.
 
 # LOCALIZATION NOTE (toolbox.viewCssSourceInStyleEditor.label)
 # Used as a message in either tooltips or contextual menu items to open the
 # corresponding URL as a css file in the Style-Editor tool.
 # DEV NOTE: Mostly used wherever toolbox.viewSourceInStyleEditor is used.
 toolbox.viewCssSourceInStyleEditor.label=Open File in Style-Editor
 
 # LOCALIZATION NOTE (toolbox.viewJsSourceInDebugger.label)

--- a/devtools/client/menus.js
+++ b/devtools/client/menus.js
@@ -107,18 +107,19 @@ exports.menuitems = [
       id: "browserToolbox",
       modifiers: "accel,alt,shift",
       keytext: true
     }
   },
   { id: "menu_browserContentToolbox",
     l10nKey: "browserContentToolboxMenu",
     disabled: true,
-    oncommand() {
-      gDevToolsBrowser.openContentProcessToolbox();
+    oncommand(event) {
+      let window = event.target.ownerDocument.defaultView;
+      gDevToolsBrowser.openContentProcessToolbox(window.gBrowser);
     }
   },
   { id: "menu_browserConsole",
     l10nKey: "browserConsoleCmd",
     oncommand() {
       let HUDService = require("devtools/client/webconsole/hudservice");
       HUDService.openBrowserConsoleOrFocus();
     },