docs(text area): fix syntax highlighting in examples (Textualize#4099)

* docs(text area): fix syntax highlighting in examples

* revert text_area_extended.py

* fix class method

* fix extended text area example

Author: TomJGooding

docs/examples/widgets/text_area_custom_language.py

@@ -18,7 +18,7 @@ class HelloWorld {
 
 class TextAreaCustomLanguage(App):
     def compose(self) -> ComposeResult:
-        text_area = TextArea(text=java_code)
+        text_area = TextArea.code_editor(text=java_code)
         text_area.cursor_blink = False
 
         # Register the Java language and highlight query

docs/examples/widgets/text_area_example.py

@@ -12,7 +12,7 @@ def goodbye(name):
 
 class TextAreaExample(App):
     def compose(self) -> ComposeResult:
-        yield TextArea(TEXT, language="python")
+        yield TextArea.code_editor(TEXT, language="python")
 
 
 app = TextAreaExample()

docs/examples/widgets/text_area_extended.py

@@ -15,7 +15,7 @@ def _on_key(self, event: events.Key) -> None:
 
 class TextAreaKeyPressHook(App):
     def compose(self) -> ComposeResult:
-        yield ExtendedTextArea(language="python")
+        yield ExtendedTextArea.code_editor(language="python")
 
 
 app = TextAreaKeyPressHook()

docs/examples/widgets/text_area_selection.py

@@ -13,7 +13,7 @@ def goodbye(name):
 
 class TextAreaSelection(App):
     def compose(self) -> ComposeResult:
-        text_area = TextArea(TEXT, language="python")
+        text_area = TextArea.code_editor(TEXT, language="python")
         text_area.selection = Selection(start=(0, 0), end=(2, 0))  # (1)!
         yield text_area
 

src/textual/widgets/_text_area.py

@@ -457,7 +457,7 @@ def code_editor(
             classes: One or more Textual CSS compatible class names separated by spaces.
             disabled: True if the widget is disabled.
         """
-        return TextArea(
+        return cls(
             text,
             language=language,
             theme=theme,