Hiding/Unhiding Apps

[ChaosCoder]

Currently, hiding an app is implemented by setting the rowId to the negative number, so it can be reversed later by again multiplying it by -1.

However, this seems to break Launchpads app ordering.

Solution: Do not set the rowId to a negative number. Instead, delete the row completely. In order to be able to unhide the item, we have to remember it somewhere (own database?).