Remove flickering between input changes

[diogox]

Right now, changing the input by adding a letter, for example, causes the launcher to delete the results, hide the scrolled window and add the new results.
That can be quite an unpleasant watch, because, sometimes, we can see the flicker caused by removing the results and adding the new ones. Maybe I should add some kind of delay before the "change" handle is executed, or simply replace the current results...