Support the Copy command in the timeline. Fix #114.

Evergreen/MainWindow/Timeline/ArticlePasteboardWriter.swift

@@ -8,6 +8,14 @@
 
 import AppKit
 import Data
+import RSCore
+
+extension Article: PasteboardWriterOwner {
+
+	public var pasteboardWriter: NSPasteboardWriting {
+		return ArticlePasteboardWriter(article: self)
+	}
+}
 
 @objc final class ArticlePasteboardWriter: NSObject, NSPasteboardWriting {
 

Evergreen/MainWindow/Timeline/TimelineViewController.swift

@@ -214,6 +214,11 @@ class TimelineViewController: NSViewController, UndoableCommandRunner {
 		runCommand(markUnreadCommand)
 	}
 
+	@IBAction func copy(_ sender: Any?) {
+
+		NSPasteboard.general.copyObjects(selectedArticles)
+	}
+
 	func markOlderArticlesAsRead() {
 
 		// Mark articles the same age or older than the selected article(s) as read.
@@ -422,6 +427,19 @@ class TimelineViewController: NSViewController, UndoableCommandRunner {
 	}
 }
 
+// MARK: NSUserInterfaceValidations
+
+extension TimelineViewController: NSUserInterfaceValidations {
+
+	func validateUserInterfaceItem(_ item: NSValidatedUserInterfaceItem) -> Bool {
+
+		if item.action == #selector(copy(_:)) {
+			return NSPasteboard.general.canCopyAtLeastOneObject(selectedArticles)
+		}
+		return true
+	}
+}
+
 // MARK: - NSTableViewDataSource
 
 extension TimelineViewController: NSTableViewDataSource {