### 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
int item_count = 0;
	bool backbuffer_cleared = false;
	bool time_used = false;
	bool material_screen_texture_cached = false;
	bool material_screen_texture_mipmaps_cached = false;
	Rect2 back_buffer_rect;
	bool backbuffer_copy = false;
	bool backbuffer_gen_mipmaps = false;
	bool update_skeletons = false;
	Item *ci = p_item_list;
	Item *canvas_group_owner = nullptr;
	bool skip_item = false;
	state.last_item_index = 0;
	while (ci) {
		if (ci->copy_back_buffer && canvas_group_owner == nullptr) {
			backbuffer_copy = true;
			if (ci->copy_back_buffer->full) {
				back_buffer_rect = Rect2();
			} else {
				back_buffer_rect = ci->copy_back_buffer->rect;
			}
		}
		
		RID material = ci->material_owner == nullptr ? ci->material : ci->material_owner->material;
		if (material.is_valid()) {
			GLES3::CanvasMaterialData *md = static_cast<GLES3::CanvasMaterialData *>(material_storage->material_get_data(material, RS::SHADER_CANVAS_ITEM));
			if (md && md->shader_data->valid) {
				if (md->shader_data->uses_screen_texture && canvas_group_owner == nullptr) {
					if (!material_screen_texture_cached) {
						backbuffer_copy = true;