### Godot version

4.1.1

### System information

linux

### Issue description

[simplescreenrecorder-2023-08-30_15.01.51.webm](https://github.com/godotengine/godot-proposals/assets/71937306/537d92b9-4f98-4fe6-adf4-71297be0471a)

I guess this wasn't the case before since I could save a layout named "2 monitors".

### Steps to reproduce

press space

### Minimal reproduction project

none
TreeItem *icon_root = edit_items_tree->create_item(root);
			icon_root->set_metadata(0, Theme::DATA_TYPE_ICON);
			icon_root->set_icon(0, get_theme_icon(SNAME("ImageTexture"), SNAME("EditorIcons")));
			icon_root->set_text(0, TTR("Icons"));
			icon_root->add_button(0, get_theme_icon(SNAME("Clear"), SNAME("EditorIcons")), ITEMS_TREE_REMOVE_DATA_TYPE, false, TTR("Remove All Icon Items"));
			names.sort_custom<StringName::AlphCompare>();
			for (const StringName &E : names) {
				TreeItem *item = edit_items_tree->create_item(icon_root);
				item->set_text(0, E);
				item->add_button(0, get_theme_icon(SNAME("Edit"), SNAME("EditorIcons")), ITEMS_TREE_RENAME_ITEM, false, TTR("Rename Item"));
				item->add_button(0, get_theme_icon(SNAME("Remove"), SNAME("EditorIcons")), ITEMS_TREE_REMOVE_ITEM, false, TTR("Remove Item"));
			}
			has_any_items = true;
		}
	}
	{ 
		names.clear();
		edited_theme->get_stylebox_list(p_item_type, &names);
		if (names.size() > 0) {
			TreeItem *stylebox_root = edit_items_tree->create_item(root);
			stylebox_root->set_metadata(0, Theme::DATA_TYPE_STYLEBOX);
			stylebox_root->set_icon(0, get_theme_icon(SNAME("StyleBoxFlat"), SNAME("EditorIcons")));
			stylebox_root->set_text(0, TTR("Styleboxes"));
			stylebox_root->add_button(0, get_theme_icon(SNAME("Clear"), SNAME("EditorIcons")), ITEMS_TREE_REMOVE_DATA_TYPE, false, TTR("Remove All StyleBox Items"));
			names.sort_custom<StringName::AlphCompare>();
			for (const StringName &E : names) {
				TreeItem *item = edit_items_tree->create_item(stylebox_root);
				item->set_text(0, E);
				item->add_button(0, get_theme_icon(SNAME("Edit"), SNAME("EditorIcons")), ITEMS_TREE_RENAME_ITEM, false, TTR("Rename Item"));
				item->add_button(0, get_theme_icon(SNAME("Remove"), SNAME("EditorIcons")), ITEMS_TREE_REMOVE_ITEM, false, TTR("Remove Item"));