### 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->add_child(zoom_hb);
	zoom_hb->set_begin(Point2(5, 5));
	zoom_out = memnew(Button);
	zoom_out->set_flat(true);
	zoom_out->set_tooltip_text(TTR("Zoom Out"));
	zoom_out->connect("pressed", callable_mp(this, &TextureRegionEditor::_zoom_out));
	zoom_hb->add_child(zoom_out);
	zoom_reset = memnew(Button);
	zoom_reset->set_flat(true);
	zoom_reset->set_tooltip_text(TTR("Zoom Reset"));
	zoom_reset->connect("pressed", callable_mp(this, &TextureRegionEditor::_zoom_reset));
	zoom_hb->add_child(zoom_reset);
	zoom_in = memnew(Button);
	zoom_in->set_flat(true);
	zoom_in->set_tooltip_text(TTR("Zoom In"));
	zoom_in->connect("pressed", callable_mp(this, &TextureRegionEditor::_zoom_in));
	zoom_hb->add_child(zoom_in);
	vscroll = memnew(VScrollBar);
	vscroll->set_step(0.001);
	edit_draw->add_child(vscroll);
	vscroll->connect("value_changed", callable_mp(this, &TextureRegionEditor::_scroll_changed));
	hscroll = memnew(HScrollBar);
	hscroll->set_step(0.001);
	edit_draw->add_child(hscroll);
	hscroll->connect("value_changed", callable_mp(this, &TextureRegionEditor::_scroll_changed));
	updating_scroll = false;
	autoslice_is_dirty = true;
	set_title(TTR("Region Editor"));
}
bool EditorInspectorPluginTextureRegion::can_handle(Object *p_object) {