### Godot version

4.0.rc6.mono.official

### System information

macOS 12.0.1

### Issue description

Just a minor visual issue.

When opening an empty directory the focus highlight is drawn incorrectly. It looks like the UI is drawing a smaller rectangle within the main rect:
<img width="1058" alt="Bildschirmfoto 2023-02-28 um 14 13 31" src="https://user-images.githubusercontent.com/11627131/221868794-7450606d-e758-4104-8f33-182d9779d7f8.png">


This behavior also changes when you hover over other items in the view, so I'm not sure if this a general issue with the focus highlighting or just an issue in the directory view:
<img width="1052" alt="Bildschirmfoto 2023-02-28 um 14 32 54" src="https://user-images.githubusercontent.com/11627131/221869308-4756f26e-cda2-4057-be1e-7439030895dc.png">


### Steps to reproduce

1. New Project
2. Browse
3. Create Folder
4. Click or Tab to set focus on the empty directory view

### Minimal reproduction project

N/A
String global_defines;
	global_defines += "#define MAX_GLOBAL_SHADER_UNIFORMS 256\n"; 
	global_defines += "#define MAX_LIGHTS " + itos(data.max_lights_per_render) + "\n";
	GLES3::MaterialStorage::get_singleton()->shaders.canvas_shader.initialize(global_defines, 1);
	data.canvas_shader_default_version = GLES3::MaterialStorage::get_singleton()->shaders.canvas_shader.version_create();
	state.shadow_texture_size = GLOBAL_GET("rendering/2d/shadow_atlas/size");
	shadow_render.shader.initialize();
	shadow_render.shader_version = shadow_render.shader.version_create();
	{
		default_canvas_group_shader = material_storage->shader_allocate();
		material_storage->shader_initialize(default_canvas_group_shader);
		material_storage->shader_set_code(default_canvas_group_shader, R"(
// Default CanvasGroup shader.
shader_type canvas_item;
render_mode unshaded;
uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;
void fragment() {
	vec4 c = textureLod(screen_texture, SCREEN_UV, 0.0);
	if (c.a > 0.0001) {
		c.rgb /= c.a;
	}
	COLOR *= c;
}
)");
		default_canvas_group_material = material_storage->material_allocate();
		material_storage->material_initialize(default_canvas_group_material);
		material_storage->material_set_shader(default_canvas_group_material, default_canvas_group_shader);
	}
	{
		default_clip_children_shader = material_storage->shader_allocate();