### 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
setting->set_initial_value("text_editor/theme/highlighting/caret_background_color", caret_background_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/text_selected_color", text_selected_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/selection_color", selection_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/brace_mismatch_color", brace_mismatch_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/current_line_color", current_line_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/line_length_guideline_color", line_length_guideline_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/word_highlighted_color", word_highlighted_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/number_color", number_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/function_color", function_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/member_variable_color", member_variable_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/mark_color", mark_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/bookmark_color", bookmark_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/breakpoint_color", breakpoint_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/executing_line_color", executing_line_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/code_folding_color", code_folding_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/search_result_color", search_result_color, true);
		setting->set_initial_value("text_editor/theme/highlighting/search_result_border_color", search_result_border_color, true);
	} else if (text_editor_color_theme == "Godot 2") {
		setting->load_text_editor_theme();
	}
	
	theme->set_font("font", "CodeEdit", theme->get_font(SNAME("source"), SNAME("EditorFonts")));
	theme->set_font_size("font_size", "CodeEdit", theme->get_font_size(SNAME("source_size"), SNAME("EditorFonts")));
	Ref<StyleBoxFlat> code_edit_stylebox = make_flat_stylebox(EDITOR_GET("text_editor/theme/highlighting/background_color"), widget_default_margin.x, widget_default_margin.y, widget_default_margin.x, widget_default_margin.y, corner_radius);
	theme->set_stylebox("normal", "CodeEdit", code_edit_stylebox);
	theme->set_stylebox("read_only", "CodeEdit", code_edit_stylebox);
	theme->set_stylebox("focus", "CodeEdit", Ref<StyleBoxEmpty>(memnew(StyleBoxEmpty)));
	theme->set_icon("tab", "CodeEdit", theme->get_icon(SNAME("GuiTab"), SNAME("EditorIcons")));
	theme->set_icon("space", "CodeEdit", theme->get_icon(SNAME("GuiSpace"), SNAME("EditorIcons")));
	theme->set_icon("folded", "CodeEdit", theme->get_icon(SNAME("CodeFoldedRightArrow"), SNAME("EditorIcons")));