doc: Enforce default values for OS properties

Otherwise we end up fetching values from the current OS instance
when running doctool, so they would change based on the system or
even simply due to changes to the system clipboard.

core/bind/core_bind.cpp

@@ -1317,6 +1317,26 @@ void _OS::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "window_position"), "set_window_position", "get_window_position");
 	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "window_size"), "set_window_size", "get_window_size");
 
+	// Those default values need to be specified for the docs generator,
+	// to avoid using values from the documentation writer's own OS instance.
+	ADD_PROPERTY_DEFAULT("clipboard", "");
+	ADD_PROPERTY_DEFAULT("current_screen", 0);
+	ADD_PROPERTY_DEFAULT("exit_code", 0);
+	ADD_PROPERTY_DEFAULT("vsync_enabled", true);
+	ADD_PROPERTY_DEFAULT("low_processor_usage_mode", false);
+	ADD_PROPERTY_DEFAULT("keep_screen_on", true);
+	ADD_PROPERTY_DEFAULT("min_window_size", Vector2());
+	ADD_PROPERTY_DEFAULT("max_window_size", Vector2());
+	ADD_PROPERTY_DEFAULT("screen_orientation", 0);
+	ADD_PROPERTY_DEFAULT("window_borderless", false);
+	ADD_PROPERTY_DEFAULT("window_per_pixel_transparency_enabled", false);
+	ADD_PROPERTY_DEFAULT("window_fullscreen", false);
+	ADD_PROPERTY_DEFAULT("window_maximized", false);
+	ADD_PROPERTY_DEFAULT("window_minimized", false);
+	ADD_PROPERTY_DEFAULT("window_resizable", true);
+	ADD_PROPERTY_DEFAULT("window_position", Vector2());
+	ADD_PROPERTY_DEFAULT("window_size", Vector2());
+
 	BIND_ENUM_CONSTANT(VIDEO_DRIVER_GLES2);
 	BIND_ENUM_CONSTANT(VIDEO_DRIVER_GLES3);
 

doc/classes/OS.xml

@@ -800,7 +800,7 @@
 		</method>
 	</methods>
 	<members>
-		<member name="clipboard" type="String" setter="set_clipboard" getter="get_clipboard" default="&quot;an editor if it were&quot;">
+		<member name="clipboard" type="String" setter="set_clipboard" getter="get_clipboard" default="&quot;&quot;">
 			The clipboard from the host OS. Might be unavailable on some platforms.
 		</member>
 		<member name="current_screen" type="int" setter="set_current_screen" getter="get_current_screen" default="0">
@@ -845,13 +845,13 @@
 			Use [code]get_tree().get_root().set_transparent_background(true)[/code] to disable main viewport background rendering.
 			[b]Note:[/b] This property has no effect if [b]Project &gt; Project Settings &gt; Display &gt; Window &gt; Per-pixel transparency &gt; Allowed[/b] setting is disabled.
 		</member>
-		<member name="window_position" type="Vector2" setter="set_window_position" getter="get_window_position" default="Vector2( 0, 436 )">
+		<member name="window_position" type="Vector2" setter="set_window_position" getter="get_window_position" default="Vector2( 0, 0 )">
 			The window position relative to the screen, the origin is the top left corner, +Y axis goes to the bottom and +X axis goes to the right.
 		</member>
 		<member name="window_resizable" type="bool" setter="set_window_resizable" getter="is_window_resizable" default="true">
 			If [code]true[/code], the window is resizable by the user.
 		</member>
-		<member name="window_size" type="Vector2" setter="set_window_size" getter="get_window_size" default="Vector2( 1024, 600 )">
+		<member name="window_size" type="Vector2" setter="set_window_size" getter="get_window_size" default="Vector2( 0, 0 )">
 			The size of the window (without counting window manager decorations).
 		</member>
 	</members>