### Godot version

v4.1.1.stable.official [bd6af8e0e]

### System information

Godot v4.1.1.stable - Ubuntu 22.04.2 LTS 22.04 - Vulkan (Forward+) - integrated Intel(R) UHD Graphics 615 (AML-KBL) () - Intel(R) Core(TM) i3-10100Y CPU @ 1.30GHz (4 Threads)

### Issue description

Summary: When editing the subregion of a StyleBoxTexture, it shows me the entire spritesheet of the Atlas texture, instead of the selected portion of the atlas, making it difficult (and non-intuitive) to correctly select the subregion I need. 

What I expect: I understand that the sub-region may be used to emulate the behavior of a nine-patch. So I would expect to see there the subregion that i selected previously from the Atlas as the texture to be shown.

I have only tested this in a Panel Container

### Steps to reproduce

I found this problem when doing these steps:

- Add a PanelContainer node
- In the inspector select Theme Overrrides -> Style -> new StyleBoxTexture
- In the texture of the StyleBoxTexture select new AtlasTexture
- Dropped the spritesheet in the Atlas of the AtlasTexture
- In Region of the AtlasTexture, selected Edit Region and drew the rectangle on the texture i want:
![image](https://github.com/godotengine/godot/assets/1207326/2e9624b1-63bc-4267-8d7f-59e82df7896e)

- Back in the StyleBoxTexture options, in Sub-Region, clicked on Edit Region to select the nine-patch region i need
- Here is where the region editor shows me the entire spritesheet and not the sub-texture i selected from the atlas. The image below shows the axis correctly positioned for the nine-patch to work, but it is not intuitive because it has to be positioned without seeing the correct texture, making it difficult to finetune for some textures.

![image](https://github.com/godotengine/godot/assets/1207326/a5023afd-7e4b-47c8-adfc-03fda7f6301b)


### Minimal reproduction project

N/A
break;
			}
		} else {
			filter = CanvasItem::TEXTURE_FILTER_NEAREST_WITH_MIPMAPS;
		}
	}
	if (texture.is_null()) {
		preview_tex->set_diffuse_texture(nullptr);
		_zoom_reset();
		hscroll->hide();
		vscroll->hide();
		edit_draw->queue_redraw();
		return;
	}
	preview_tex->set_texture_filter(filter);
	preview_tex->set_diffuse_texture(texture);
	if (cache_map.has(texture->get_rid())) {
		autoslice_cache = cache_map[texture->get_rid()];
		autoslice_is_dirty = false;
	} else {
		if (is_visible() && snap_mode == SNAP_AUTOSLICE) {
			_update_autoslice();
		} else {
			autoslice_is_dirty = true;
		}
	}
	_update_rect();
	edit_draw->queue_redraw();
}
Vector2 TextureRegionEditor::snap_point(Vector2 p_target) const {