For Canadians who like to wear rose-coloured glasses, Globe and Mail Reporter Hugh Winsor's description of a historic immigration decision made in late October 1990 will be too damning to take. Mr. Winsor was reporting on the decision of Canada's Immigration Minister, Barbara McDougall, to increase immigration levels to 250,000 in order for her party to get a larger percentage of the immigrant vote. Even Canadians who are more realistic will probably be bothered by the brazen shamelessness of the decision.