You initiated an action: Unzip or Mount an installer. 99% of the time I want that brought to front. Stealing focus is only bad when you did not initiate that action, hence why popups are hated so much.
I agree with your premise, but I would like to point out that there is often a significant delay between clicking on a .dmg download and there being some action.
I know that I am unlikely to sit idly and watch the download progress-bar; I'm far more likely to switch to some other tab or other application. And then, since my focus is elsewhere, we have returned to the focus stealing situation.
I know that I am unlikely to sit idly and watch the download progress-bar; I'm far more likely to switch to some other tab or other application. And then, since my focus is elsewhere, we have returned to the focus stealing situation.