### Godot version

4.x

### System information

Windows 10

### Issue description

The `Search Result` panel is not correctly updated when changing the theme.

https://user-images.githubusercontent.com/66004280/208964493-d0423b78-3418-44c9-95ed-822fd34c4720.mp4



### Steps to reproduce

1. Search something
2. Change the theme

### Minimal reproduction project

--
switch (p_what) {
		case NOTIFICATION_PROCESS: {
			_process();
		} break;
	}
}
void FindInFiles::start() {
	if (_pattern.is_empty()) {
		print_verbose("Nothing to search, pattern is empty");
		emit_signal(SNAME(SIGNAL_FINISHED));
		return;
	}
	if (_extension_filter.size() == 0) {
		print_verbose("Nothing to search, filter matches no files");
		emit_signal(SNAME(SIGNAL_FINISHED));
		return;
	}
	
	_current_dir = "";
	PackedStringArray init_folder;
	init_folder.push_back(_root_dir);
	_folders_stack.clear();
	_folders_stack.push_back(init_folder);
	_initial_files_count = 0;
	_searching = true;
	set_process(true);
}
void FindInFiles::stop() {