### 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
uint32_t instance_color_offset = 0;
			bool instance_uses_color = false;
			bool instance_uses_custom_data = false;
			bool use_instancing = false;
			if (state.canvas_instance_batches[p_index].command_type == Item::Command::TYPE_MESH) {
				const Item::CommandMesh *m = static_cast<const Item::CommandMesh *>(state.canvas_instance_batches[p_index].command);
				mesh = m->mesh;
				mesh_instance = m->mesh_instance;
			} else if (state.canvas_instance_batches[p_index].command_type == Item::Command::TYPE_MULTIMESH) {
				const Item::CommandMultiMesh *mm = static_cast<const Item::CommandMultiMesh *>(state.canvas_instance_batches[p_index].command);
				RID multimesh = mm->multimesh;
				mesh = mesh_storage->multimesh_get_mesh(multimesh);
				if (mesh_storage->multimesh_get_transform_format(multimesh) != RS::MULTIMESH_TRANSFORM_2D) {
					break;
				}
				instance_count = mesh_storage->multimesh_get_instances_to_draw(multimesh);
				if (instance_count == 0) {
					break;
				}
				instance_buffer = mesh_storage->multimesh_get_gl_buffer(multimesh);
				instance_stride = mesh_storage->multimesh_get_stride(multimesh);
				instance_color_offset = mesh_storage->multimesh_get_color_offset(multimesh);
				instance_uses_color = mesh_storage->multimesh_uses_colors(multimesh);
				instance_uses_custom_data = mesh_storage->multimesh_uses_custom_data(multimesh);
				use_instancing = true;
			} else if (state.canvas_instance_batches[p_index].command_type == Item::Command::TYPE_PARTICLES) {
				const Item::CommandParticles *pt = static_cast<const Item::CommandParticles *>(state.canvas_instance_batches[p_index].command);
				RID particles = pt->particles;
				mesh = particles_storage->particles_get_draw_pass_mesh(particles, 0);
				ERR_BREAK(particles_storage->particles_get_mode(particles) != RS::PARTICLES_MODE_2D);