Does anyone do windows any more? I don't mean the clear panes of glass in our homes, long the object of the punch line of abject-housekeeper jokes, but the on-screen ''Now you can run half a dozen programs at once'' variety. The answer is, not really. Windows, which had been announced as early as 1982, were the hot concept for 1984, as mice were for 1983. But where mice have found their niche, windows were seen through by the consumer. The idea had been that your computer, using windows, could display small segments of a number of programs at the same time, coordinating them on the monitor screen.