Trade mark law does not forbid trade marks on common language words and phrases. It generally prevents people from registering 'descriptive' or 'non-distinctive

Trade mark law does not forbid trade marks on common language words and phrases. It generally prevents people from registering 'descriptive' or 'non-distinctive' words/phrases as trade marks. "Windows" is descriptive for glazing supplies so wouldn't be registrable. "Windows" for software is distinctive and there is no public interest in it remaining free for anyone to use, unlike the case with the glazing example.