Created attachment 187541 [details] [review]
implements the described behaviour

This patch adds support in the overview view for launching apps in the background (i.e without closing the overview) when SHIFT is held down. Since this is of no use for switching apps, it also ensures a new window is created (like CTRL does).

The use cases are:
 - launching multiple apps at a time (e.g on login, launch the browser, music player & terminal window all from the dock). This is currently very tedious, as the user has to tap the windows key between each app launch (or keep mousing over the activities hot corner)

 - launching one or more apps in a new workspace (when combined with middle-click) - this could be a good solution for bug 643830