Changed how borderless setting works.

ptlinux/settings.py

@@ -15,6 +15,7 @@ from .paths import AppPaths
 
 
 SETTINGS_SCHEMA = 1
+_TITLE_FRAME_DEFAULT_MIGRATION_KEY = "title_frame_default_migrated"
 
 
 @dataclass(frozen=True)
@@ -26,7 +27,7 @@ class Settings:
 	output_height: int = 900
 	refresh_rate: int = 60
 	fullscreen: bool = False
-	borderless: bool = True
+	borderless: bool = False
 	suppress_unresponsive_warnings: bool = True
 	scaler: str = "fit"
 	filter: str = "linear"
@@ -141,7 +142,7 @@ def _settings_from_object(value: dict[str, object]) -> Settings:
 		output_height=_integer(value, "output_height", 900),
 		refresh_rate=_integer(value, "refresh_rate", 60),
 		fullscreen=_boolean(value, "fullscreen", False),
-		borderless=_boolean(value, "borderless", True),
+		borderless=_migrated_borderless(value),
 		suppress_unresponsive_warnings=_boolean(
 			value,
 			"suppress_unresponsive_warnings",
@@ -158,6 +159,22 @@ def _settings_from_object(value: dict[str, object]) -> Settings:
 	return settings
 
 
+def _migrated_borderless(value: dict[str, object]) -> bool:
+	"""Retire the old implicit borderless default exactly once.
+
+	Older releases wrote ``borderless=true`` for every default installation, so
+	they cannot distinguish an inherited value from an explicit choice. The
+	migration marker keeps schema 1 backward compatible while letting users opt
+	back into Borderless after the decorated default has been applied.
+	"""
+
+	borderless = _boolean(value, "borderless", False)
+	migrated = _boolean(value, _TITLE_FRAME_DEFAULT_MIGRATION_KEY, False)
+	if not migrated:
+		return False
+	return borderless
+
+
 def _decode_settings(content: bytes) -> str:
 	"""Accept native UTF-8 plus settings saved by common Windows editors."""
 
@@ -174,6 +191,7 @@ def _settings_need_migration(value: dict[str, object]) -> bool:
 	return (
 		value.get("schema") != SETTINGS_SCHEMA
 		or not _SETTINGS_FIELD_NAMES.issubset(value)
+		or value.get(_TITLE_FRAME_DEFAULT_MIGRATION_KEY) is not True
 	)
 
 
@@ -185,6 +203,7 @@ def _write_settings(
 	payload = dict(existing or {})
 	payload.update(asdict(settings))
 	payload["schema"] = SETTINGS_SCHEMA
+	payload[_TITLE_FRAME_DEFAULT_MIGRATION_KEY] = True
 	temporary = paths.settings_file.with_name(
 		f".{paths.settings_file.name}.{os.getpid()}.{threading.get_ident()}."
 		f"{secrets.token_hex(8)}.tmp"