### 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
const Color member_variable_color = dark_theme ? Color(0.34, 0.7, 1.0).lerp(mono_color, 0.6) : Color(0, 0.4, 0.68, 1);
	const Color mark_color = Color(error_color.r, error_color.g, error_color.b, 0.3);
	const Color bookmark_color = Color(0.08, 0.49, 0.98);
	const Color breakpoint_color = dark_theme ? error_color : Color(1, 0.27, 0.2, 1);
	const Color executing_line_color = Color(0.98, 0.89, 0.27);
	const Color code_folding_color = alpha3;
	const Color search_result_color = alpha1;
	const Color search_result_border_color = dark_theme ? Color(0.41, 0.61, 0.91, 0.38) : Color(0, 0.4, 1, 0.38);
	EditorSettings *setting = EditorSettings::get_singleton();
	String text_editor_color_theme = setting->get("text_editor/theme/color_theme");
	if (text_editor_color_theme == "Default") {
		setting->set_initial_value("text_editor/theme/highlighting/symbol_color", symbol_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/keyword_color", keyword_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/control_flow_keyword_color", control_flow_keyword_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/base_type_color", base_type_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/engine_type_color", engine_type_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/user_type_color", user_type_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/comment_color", comment_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/string_color", string_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/background_color", te_background_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_background_color", completion_background_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_selected_color", completion_selected_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_existing_color", completion_existing_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_scroll_color", completion_scroll_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_scroll_hovered_color", completion_scroll_hovered_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/completion_font_color", completion_font_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/text_color", text_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/line_number_color", line_number_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/safe_line_number_color", safe_line_number_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/caret_color", caret_color, true);