Fix split editor button

CHANGELOG.md

@@ -2,7 +2,16 @@
 Change Log
 ==========================
 
-4.0.0 (unreleased)
+4.0.0-beta.2 (unreleased)
+--------------------------
+
+### Fixes
+
+- [beta] fix an issue in the navigation bar that the split editor button did not updated when change the split orientation.
+
+
+
+4.0.0-beta (442)
 --------------------------
 
 ### New Features

CotEditor/Assets.xcassets/Templates/split.add-vertical.imageset/Contents.json

@@ -1,7 +1,7 @@
 {
   "images" : [
     {
-      "filename" : "split.add.vertical.pdf",
+      "filename" : "split.add-vertical.pdf",
       "idiom" : "universal"
     }
   ],

CotEditor/Sources/NavigationBarController.swift

@@ -92,7 +92,8 @@ final class NavigationBarController: NSViewController {
             else { return assertionFailure() }
         
         splitViewController.$isVertical
-            .map { $0 ? #imageLiteral(resourceName: "split.add.vertical") : #imageLiteral(resourceName: "split.add") }
+            .map { $0 ? "split.add-vertical" : "split.add" }
+            .map { NSImage(named: $0) }
             .assign(to: \.image, on: self.openSplitButton!)
             .store(in: &self.splitViewObservers)
         splitViewController.$canCloseSplitItem