### 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
_EIDX(2, 0), _EIDX(2, 1), _EIDX(3, 1),
			_EIDX(3, 1), _EIDX(3, 0), _EIDX(2, 0),
			_EIDX(2, 1), _EIDX(2, 2), _EIDX(3, 2),
			_EIDX(3, 2), _EIDX(3, 1), _EIDX(2, 1),
			_EIDX(2, 2), _EIDX(2, 3), _EIDX(3, 3),
			_EIDX(3, 3), _EIDX(3, 2), _EIDX(2, 2),
			
			_EIDX(1, 1), _EIDX(1, 2), _EIDX(2, 2),
			_EIDX(2, 2), _EIDX(2, 1), _EIDX(1, 1)
		};
#undef _EIDX
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elems), elems, GL_STATIC_DRAW);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	}
	int uniform_max_size = config->max_uniform_buffer_size;
	if (uniform_max_size < 65536) {
		data.max_lights_per_render = 64;
	} else {
		data.max_lights_per_render = 256;
	}
	
	data.max_instances_per_buffer = uint32_t(GLOBAL_GET("rendering/gl_compatibility/item_buffer_size"));
	data.max_instance_buffer_size = data.max_instances_per_buffer * sizeof(InstanceData); 
	state.canvas_instance_data_buffers.resize(3);
	state.canvas_instance_batches.reserve(200);
	for (int i = 0; i < 3; i++) {
		GLuint new_buffers[3];
		glGenBuffers(3, new_buffers);