fix: plugin menu button in ScriptEditor to match other topbar buttons (#216)

Author: elliotfontaine

addons/GDQuest_GDScript_formatter/menu.gd

@@ -30,7 +30,9 @@ func _ready() -> void:
 
 	menu_button = MenuButton.new()
 	menu_button.text = MENU_TEXT
-	menu_button.flat = true
+	menu_button.switch_on_hover = true
+	menu_button.flat = false
+	menu_button.theme_type_variation = &"FlatMenuButton"
 
 	popup_menu = menu_button.get_popup()
 	_populate_menu()