11 files changed, 11 insertions, 0 deletions
diff --git a/ext/tk/sample/tkextlib/treectrl/bitmaps.rb b/ext/tk/sample/tkextlib/treectrl/bitmaps.rb
index 0d8b37b81e..a42e7ac541 100644
--- a/ext/tk/sample/tkextlib/treectrl/bitmaps.rb
+++ b/ext/tk/sample/tkextlib/treectrl/bitmaps.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: Bitmaps
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/demo.rb b/ext/tk/sample/tkextlib/treectrl/demo.rb
index 564a005bdc..cd277cf2a9 100644
--- a/ext/tk/sample/tkextlib/treectrl/demo.rb
+++ b/ext/tk/sample/tkextlib/treectrl/demo.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: false
 
 require 'tk'
 require 'tkextlib/treectrl'
diff --git a/ext/tk/sample/tkextlib/treectrl/explorer.rb b/ext/tk/sample/tkextlib/treectrl/explorer.rb
index 1b8c2a8287..3b54bf269c 100644
--- a/ext/tk/sample/tkextlib/treectrl/explorer.rb
+++ b/ext/tk/sample/tkextlib/treectrl/explorer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 
 def demoExplorerAux(t, dir_proc, file_proc)
   base_dir = File.dirname(File.dirname(@ScriptDir))
diff --git a/ext/tk/sample/tkextlib/treectrl/help.rb b/ext/tk/sample/tkextlib/treectrl/help.rb
index 31ec9eb3f8..e3758d00a6 100644
--- a/ext/tk/sample/tkextlib/treectrl/help.rb
+++ b/ext/tk/sample/tkextlib/treectrl/help.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: Help contents
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/imovie.rb b/ext/tk/sample/tkextlib/treectrl/imovie.rb
index 72134ebda6..4419496ac4 100644
--- a/ext/tk/sample/tkextlib/treectrl/imovie.rb
+++ b/ext/tk/sample/tkextlib/treectrl/imovie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: iMovie
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/layout.rb b/ext/tk/sample/tkextlib/treectrl/layout.rb
index 488abe2aa9..50c332641b 100644
--- a/ext/tk/sample/tkextlib/treectrl/layout.rb
+++ b/ext/tk/sample/tkextlib/treectrl/layout.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: Layout
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/mailwasher.rb b/ext/tk/sample/tkextlib/treectrl/mailwasher.rb
index 1b51bb9b21..81ffe743b6 100644
--- a/ext/tk/sample/tkextlib/treectrl/mailwasher.rb
+++ b/ext/tk/sample/tkextlib/treectrl/mailwasher.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: MailWasher
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/outlook-folders.rb b/ext/tk/sample/tkextlib/treectrl/outlook-folders.rb
index d966807866..8707251ee9 100644
--- a/ext/tk/sample/tkextlib/treectrl/outlook-folders.rb
+++ b/ext/tk/sample/tkextlib/treectrl/outlook-folders.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: Outlook Express folder list
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/outlook-newgroup.rb b/ext/tk/sample/tkextlib/treectrl/outlook-newgroup.rb
index 3495522e5c..841f330919 100644
--- a/ext/tk/sample/tkextlib/treectrl/outlook-newgroup.rb
+++ b/ext/tk/sample/tkextlib/treectrl/outlook-newgroup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 # Demo: Outlook Express newsgroup messages
 #
diff --git a/ext/tk/sample/tkextlib/treectrl/random.rb b/ext/tk/sample/tkextlib/treectrl/random.rb
index 43aca63283..33bbcc2631 100644
--- a/ext/tk/sample/tkextlib/treectrl/random.rb
+++ b/ext/tk/sample/tkextlib/treectrl/random.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 #
 def random_N
   @RandomN[0] || 500
diff --git a/ext/tk/sample/tkextlib/treectrl/www-options.rb b/ext/tk/sample/tkextlib/treectrl/www-options.rb
index 6a3e9c2201..81f5349abc 100644
--- a/ext/tk/sample/tkextlib/treectrl/www-options.rb
+++ b/ext/tk/sample/tkextlib/treectrl/www-options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 def demoInternetOptions (t)
   @Option = TkVarAccess.new_hash('::Option')