### 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
edit_draw->draw_line(endpoints[i] - draw_ofs * draw_zoom, endpoints[next] - draw_ofs * draw_zoom, Color(0.3, 0.7, 1, 1), 2);
			}
		}
	}
	Ref<Texture2D> select_handle = get_theme_icon(SNAME("EditorHandle"), SNAME("EditorIcons"));
	Rect2 scroll_rect(Point2(), base_tex->get_size());
	const Vector2 raw_endpoints[4] = {
		rect.position,
		rect.position + Vector2(rect.size.x, 0),
		rect.position + rect.size,
		rect.position + Vector2(0, rect.size.y)
	};
	const Vector2 endpoints[4] = {
		mtx.basis_xform(raw_endpoints[0]),
		mtx.basis_xform(raw_endpoints[1]),
		mtx.basis_xform(raw_endpoints[2]),
		mtx.basis_xform(raw_endpoints[3])
	};
	for (int i = 0; i < 4; i++) {
		int prev = (i + 3) % 4;
		int next = (i + 1) % 4;
		Vector2 ofs = ((endpoints[i] - endpoints[prev]).normalized() + ((endpoints[i] - endpoints[next]).normalized())).normalized();
		ofs *= Math_SQRT2 * (select_handle->get_size().width / 2);
		edit_draw->draw_line(endpoints[i] - draw_ofs * draw_zoom, endpoints[next] - draw_ofs * draw_zoom, color, 2);
		if (snap_mode != SNAP_AUTOSLICE) {
			edit_draw->draw_texture(select_handle, (endpoints[i] + ofs - (select_handle->get_size() / 2)).floor() - draw_ofs * draw_zoom);
		}
		ofs = (endpoints[next] - endpoints[i]) / 2;
		ofs += (endpoints[next] - endpoints[i]).orthogonal().normalized() * (select_handle->get_size().width / 2);
		if (snap_mode != SNAP_AUTOSLICE) {