How to extend editor theme?

Godot Version

4.4

Question

Hi!
I want to extend godot editor theme with custom items. So, basically, I want to write a module with some gui controls which will be used in editor plugin. I want those controls to have custom theme items, and I want the editor user to have ability to override those items. I don’t want to hardcode them and I don’t want to require a custom theme file to have the ability to use my module (default theme should have defaults). But I don’t see if it’s possible. I see the godot theme is generated in EditorThemeManager::_create_base_theme but I don’t see any way to extend it. Am I missing something?