### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
scene_root->set_snap_2d_transforms_to_pixel(snap_2d_transforms);
	bool snap_2d_vertices = GLOBAL_GET("rendering/2d/snap/snap_2d_vertices_to_pixel");
	scene_root->set_snap_2d_vertices_to_pixel(snap_2d_vertices);
	Viewport::SDFOversize sdf_oversize = Viewport::SDFOversize(int(GLOBAL_GET("rendering/2d/sdf/oversize")));
	scene_root->set_sdf_oversize(sdf_oversize);
	Viewport::SDFScale sdf_scale = Viewport::SDFScale(int(GLOBAL_GET("rendering/2d/sdf/scale")));
	scene_root->set_sdf_scale(sdf_scale);
	Viewport::MSAA msaa = Viewport::MSAA(int(GLOBAL_GET("rendering/anti_aliasing/quality/msaa_2d")));
	scene_root->set_msaa_2d(msaa);
	float mesh_lod_threshold = GLOBAL_GET("rendering/mesh_lod/lod_change/threshold_pixels");
	scene_root->set_mesh_lod_threshold(mesh_lod_threshold);
	RS::get_singleton()->decals_set_filter(RS::DecalFilter(int(GLOBAL_GET("rendering/textures/decals/filter"))));
	RS::get_singleton()->light_projectors_set_filter(RS::LightProjectorFilter(int(GLOBAL_GET("rendering/textures/light_projectors/filter"))));
	SceneTree *tree = get_tree();
	tree->set_debug_collisions_color(GLOBAL_GET("debug/shapes/collision/shape_color"));
	tree->set_debug_collision_contact_color(GLOBAL_GET("debug/shapes/collision/contact_color"));
#ifdef DEBUG_ENABLED
	NavigationServer3D::get_singleton()->set_debug_navigation_edge_connection_color(GLOBAL_GET("debug/shapes/navigation/edge_connection_color"));
	NavigationServer3D::get_singleton()->set_debug_navigation_geometry_edge_color(GLOBAL_GET("debug/shapes/navigation/geometry_edge_color"));
	NavigationServer3D::get_singleton()->set_debug_navigation_geometry_face_color(GLOBAL_GET("debug/shapes/navigation/geometry_face_color"));
	NavigationServer3D::get_singleton()->set_debug_navigation_geometry_edge_disabled_color(GLOBAL_GET("debug/shapes/navigation/geometry_edge_disabled_color"));
	NavigationServer3D::get_singleton()->set_debug_navigation_geometry_face_disabled_color(GLOBAL_GET("debug/shapes/navigation/geometry_face_disabled_color"));
	NavigationServer3D::get_singleton()->set_debug_navigation_enable_edge_connections(GLOBAL_GET("debug/shapes/navigation/enable_edge_connections"));
	NavigationServer3D::get_singleton()->set_debug_navigation_enable_edge_connections_xray(GLOBAL_GET("debug/shapes/navigation/enable_edge_connections_xray"));
	NavigationServer3D::get_singleton()->set_debug_navigation_enable_edge_lines(GLOBAL_GET("debug/shapes/navigation/enable_edge_lines"));
	NavigationServer3D::get_singleton()->set_debug_navigation_enable_edge_lines_xray(GLOBAL_GET("debug/shapes/navigation/enable_edge_lines_xray"));
	NavigationServer3D::get_singleton()->set_debug_navigation_enable_geometry_face_random_color(GLOBAL_GET("debug/shapes/navigation/enable_geometry_face_random_color"));
#endif 
}
void EditorNode::_select_default_main_screen_plugin() {