Make shift key invert the "open in background" preference

- Also add an appropriate menu item.

Mac/Base.lproj/Main.storyboard

@@ -496,6 +496,12 @@
                                                 <action selector="openArticleInBrowser:" target="Ady-hI-5gd" id="KeH-ES-fpo"/>
                                             </connections>
                                         </menuItem>
+                                        <menuItem title="Open in Browser Inverted" alternate="YES" keyEquivalent="" id="EjD-X9-Pjf">
+                                            <modifierMask key="keyEquivalentModifierMask" shift="YES" command="YES"/>
+                                            <connections>
+                                                <action selector="openArticleInBrowser:" target="Ady-hI-5gd" id="Frq-Uo-DQs"/>
+                                            </connections>
+                                        </menuItem>
                                     </items>
                                 </menu>
                             </menuItem>

Mac/Browser.swift

@@ -6,14 +6,16 @@
 //  Copyright © 2016 Ranchero Software, LLC. All rights reserved.
 //
 
-import Foundation
+import AppKit
 import RSWeb
 
 struct Browser {
 
 	static func open(_ urlString: String) {
+		let shouldInvertPreference = NSApp.currentEvent?.modifierFlags.contains(.shift) ?? false
+
 		// Opens according to prefs.
-		open(urlString, inBackground: AppDefaults.openInBrowserInBackground)
+		open(urlString, inBackground: shouldInvertPreference ? !AppDefaults.openInBrowserInBackground : AppDefaults.openInBrowserInBackground)
 	}
 
 	static func open(_ urlString: String, inBackground: Bool) {
@@ -23,3 +25,13 @@ struct Browser {
 	}
 }
 
+extension Browser {
+
+	static var titleForOpenInBrowserInverted: String {
+		let openInBackgroundPref = AppDefaults.openInBrowserInBackground
+
+		return openInBackgroundPref ?
+			NSLocalizedString("Open in Browser in Foreground", comment: "Open in Browser in Foreground menu item title") :
+			NSLocalizedString("Open in Browser in Background", comment: "Open in Browser in Background menu item title")
+	}
+}

Mac/MainWindow/MainWindowController.swift

@@ -179,6 +179,10 @@ class MainWindowController : NSWindowController, NSUserInterfaceValidations {
 	public func validateUserInterfaceItem(_ item: NSValidatedUserInterfaceItem) -> Bool {
 		
 		if item.action == #selector(openArticleInBrowser(_:)) {
+			if let item = item as? NSMenuItem, item.keyEquivalentModifierMask.contains(.shift) {
+				item.title = Browser.titleForOpenInBrowserInverted
+			}
+			
 			return currentLink != nil
 		}
 		

Mac/MainWindow/Timeline/TimelineViewController.swift

@@ -725,6 +725,10 @@ extension TimelineViewController: NSUserInterfaceValidations {
 
 	func validateUserInterfaceItem(_ item: NSValidatedUserInterfaceItem) -> Bool {
 		if item.action == #selector(openArticleInBrowser(_:)) {
+			if let item = item as? NSMenuItem, item.keyEquivalentModifierMask.contains(.shift) {
+				item.title = Browser.titleForOpenInBrowserInverted
+			}
+
 			let currentLink = oneSelectedArticle?.preferredLink
 			return currentLink != nil
 		}