Fix textContainer size after spliting editor

CHANGELOG.md

@@ -11,7 +11,7 @@ Change Log
 - Make space to draw the invisible symbol for ZERO WIDTH SPACE (U+200B) when the “other invisible characters” option is enabled.
 - Enable “Move Line Down” and “Move Line Up” commands swap lines with the last empty line.
 - Improve general performance while typing.
-- [tirivial] Keep the visible area after resizing document window even if overscrolling is enabled.
+- [tirivial] Keep the visible area after resizing a document window even if overscrolling is enabled.
 - [trivial] Adjust the theme “Note”.
 
 
@@ -22,10 +22,11 @@ Change Log
 - Fix an issue where default theme change in the preferences was not applied to opened documents under specific conditions.
 - Fix an issue where unescaping replacement string in the regular expression replacement failed with specific text patterns.
 - Fix an issue where the editor's line height and tab width in the opened windows did not update even the setting is changed.
-- Fix an isue where the rainbow cursor could appear when finding the brace pair in the latter part of a large document.
+- Fix an issue where the rainbow cursor could appear when finding the brace pair in the latter part of a large document.
 - Fix an issue where the application crashed when moving lines down under specific conditions.
 - Fix an issue where the “Sort by Pattern” with column sort key dropped the last character from the sort key string.
 - Fix an issue where the current line highlight remained when quickly moving selection by dragging.
+- Fix an issue where the writable area of newly added split editors shrank.
 - Fix an issue in scripting where settings some properties, such as `tab width`, `tab expands` and `wrap lines`, in the document creation phase were ignored.
 - Improve stability.
 

CotEditor/Sources/DocumentViewController.swift

@@ -793,18 +793,18 @@ final class DocumentViewController: NSSplitViewController, SyntaxParserDelegate,
     /// split editor view
     @IBAction func openSplitTextView(_ sender: Any?) {
         
-        guard (self.splitViewController?.splitViewItems.count ?? 0) < maximumNumberOfSplitEditors else {
-            NSSound.beep()
-            return
-        }
+        guard
+            let splitViewController = self.splitViewController,
+            let currentEditorViewController = self.findTargetEditorViewController(for: sender)
+            else { return assertionFailure() }
         
-        guard let currentEditorViewController = self.findTargetEditorViewController(for: sender) else { return }
+        guard splitViewController.splitViewItems.count < maximumNumberOfSplitEditors else { return NSSound.beep() }
         
         // end current editing
         NSTextInputContext.current?.discardMarkedText()
         
         let newEditorViewController = EditorViewController.instantiate(storyboard: "EditorView")
-        self.splitViewController?.addSubview(for: newEditorViewController, relativeTo: currentEditorViewController)
+        splitViewController.addSubview(for: newEditorViewController, relativeTo: currentEditorViewController)
         self.setup(editorViewController: newEditorViewController, baseViewController: currentEditorViewController)
         
         newEditorViewController.navigationBarController?.outlineItems = self.syntaxParser?.outlineItems ?? []

CotEditor/Sources/SplitViewController.swift

@@ -112,13 +112,11 @@ final class SplitViewController: NSSplitViewController {
     func addSubview(for editorViewController: EditorViewController, relativeTo otherEditorViewController: EditorViewController?) {
         
         let splitViewItem = NSSplitViewItem(viewController: editorViewController)
-        
         splitViewItem.holdingPriority = NSLayoutConstraint.Priority(251)
         
         if let otherEditorViewController = otherEditorViewController {
             guard let baseIndex = self.children.firstIndex(of: otherEditorViewController) else {
-                assertionFailure("The base editor view is not belong to the same window.")
-                return
+                return assertionFailure("The base editor view is not belong to the same window.")
             }
             
             self.insertSplitViewItem(splitViewItem, at: baseIndex + 1)
@@ -127,8 +125,6 @@ final class SplitViewController: NSSplitViewController {
             self.addSplitViewItem(splitViewItem)
         }
         
-        self.splitView.layoutSubtreeIfNeeded()
-        
         self.invalidateOpenSplitEditorButtons()
         self.invalidateCloseSplitEditorButtons()
     }