Add tooltip for “Show Sidebar” menu item

Author: 1024jp

CHANGELOG.md

@@ -7,6 +7,7 @@
 
 - Revert the steppers to the font setting controls in the Appearance settings pane.
 - Remove the Script menu from the context menu.
+- Add a help tag for “Show Sidebar” menu item when the command is unavailable.
 - Update the Swift syntax to support highlighting regex literals.
 
 

CotEditor/Resources/Localizables/Application/MainMenu.xcstrings

@@ -4601,6 +4601,47 @@
         }
       }
     },
+    "The sidebar is only available when a folder is opened as a document." : {
+      "comment" : "tooltip for the “Show Sidebar” menu item",
+      "localizations" : {
+        "de" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "Die Seitenleiste ist nur verfügbar, wenn ein Ordner als Dokument geöffnet ist."
+          }
+        },
+        "en-GB" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "The sidebar is only available when a folder is opened as a document."
+          }
+        },
+        "es" : {
+          "stringUnit" : {
+            "state" : "needs_review",
+            "value" : "La barra lateral sólo está disponible cuando se abre una carpeta como documento."
+          }
+        },
+        "fr" : {
+          "stringUnit" : {
+            "state" : "needs_review",
+            "value" : "La barre latérale n'est disponible que lorsqu'un dossier est ouvert en tant que document."
+          }
+        },
+        "ja" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "サイドバーはフォルダを書類として開いたときのみ有効です。"
+          }
+        },
+        "nl" : {
+          "stringUnit" : {
+            "state" : "needs_review",
+            "value" : "De navigatiekolom is alleen beschikbaar als een map als document wordt geopend."
+          }
+        }
+      }
+    },
     "To show invisible characters, set them in the Window settings" : {
       "comment" : "tooltip for the “Show Invisibles” menu item and toolbar item for when all invisible settings are disabled",
       "localizations" : {

CotEditor/Sources/Document Window/WindowContentViewController.swift

@@ -8,7 +8,7 @@
 //
 //  ---------------------------------------------------------------------------
 //
-//  © 2016-2024 1024jp
+//  © 2016-2025 1024jp
 //
 //  Licensed under the Apache License, Version 2.0 (the "License");
 //  you may not use this file except in compliance with the License.
@@ -187,12 +187,21 @@ final class WindowContentViewController: NSSplitViewController, NSToolbarItemVal
         switch item.action {
             case #selector(showFileBrowser):
                 (item as? NSMenuItem)?.state = (self.sidebarViewItem?.isCollapsed == true) ? .on : .off
+                (item as? NSMenuItem)?.toolTip = (self.sidebarViewItem == nil)
+                    ? String(localized: "The sidebar is only available when a folder is opened as a document.",
+                             table: "MainMenu", comment: "tooltip for the “Show Sidebar” menu item")
+                    : nil
                 return self.sidebarViewItem != nil
 
             case #selector(toggleSidebar):
+                // The menu item is not validated when the responder has no sidebar (2025-03, macOS 15).
                 (item as? NSMenuItem)?.title = self.sidebarViewItem?.isCollapsed == false
                     ? String(localized: "Hide Sidebar", table: "MainMenu")
                     : String(localized: "Show Sidebar", table: "MainMenu")
+                (item as? NSMenuItem)?.toolTip = (self.sidebarViewItem == nil)
+                    ? String(localized: "The sidebar is only available when a folder is opened as a document.",
+                             table: "MainMenu", comment: "tooltip for the “Show Sidebar” menu item")
+                    : nil
                 return self.sidebarStateCache == nil
 
             case #selector(toggleInspector):