### 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
draw_margin_line(edit_draw, pos[1], pos[1] + Vector2(edit_draw->get_size().x, 0));
		draw_margin_line(edit_draw, pos[2], pos[2] + Vector2(0, edit_draw->get_size().y));
		draw_margin_line(edit_draw, pos[3], pos[3] + Vector2(0, edit_draw->get_size().y));
	}
}
void TextureRegionEditor::_region_input(const Ref<InputEvent> &p_input) {
	if (panner->gui_input(p_input)) {
		return;
	}
	Transform2D mtx;
	mtx.columns[2] = -draw_ofs * draw_zoom;
	mtx.scale_basis(Vector2(draw_zoom, draw_zoom));
	const real_t handle_radius = 8 * EDSCALE;
	const real_t handle_offset = 4 * EDSCALE;
	
	const Vector2 endpoints[8] = {
		mtx.xform(rect.position) + Vector2(-handle_offset, -handle_offset),
		mtx.xform(rect.position + Vector2(rect.size.x / 2, 0)) + Vector2(0, -handle_offset),
		mtx.xform(rect.position + Vector2(rect.size.x, 0)) + Vector2(handle_offset, -handle_offset),
		mtx.xform(rect.position + Vector2(rect.size.x, rect.size.y / 2)) + Vector2(handle_offset, 0),
		mtx.xform(rect.position + rect.size) + Vector2(handle_offset, handle_offset),
		mtx.xform(rect.position + Vector2(rect.size.x / 2, rect.size.y)) + Vector2(0, handle_offset),
		mtx.xform(rect.position + Vector2(0, rect.size.y)) + Vector2(-handle_offset, handle_offset),
		mtx.xform(rect.position + Vector2(0, rect.size.y / 2)) + Vector2(-handle_offset, 0)
	};
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	Ref<InputEventMouseButton> mb = p_input;
	if (mb.is_valid()) {
		if (mb->get_button_index() == MouseButton::LEFT) {
			if (mb->is_pressed() && !panner->is_panning()) {