Because there's nothing (in single-monitor setups) that could
take the drop in this case.
* js/ui/appDisplay.js:
AllView._loadApps(), FrequentView._loadApps(): Pass
an isDraggable parameter when creating the AppIcons,
depending on whether the favorite-apps key is locked.
AppIcon._init(): Check for isDraggable in the params and
do not create _draggable if it was specified, to prevent a
drag from starting.
AppIcon.popupMenu(): Check _draggable before trying to call
fakeRelease on it.
* js/ui/dash.js: Dash._createAppItem(): Check AppIcon._draggable
before trying to connect to its signals.
https://bugzilla.gnome.org/show_bug.cgi?id=741325
1da9546c40