Debugger and duchain hints overlaps

[David Nolden]

The overlap is simply a bug somewhere in the
ActiveToolTipManager::doVisibility function. It is supposed to stack
the tooltips above each other, ordered by the 'priority' value.

To show only exactly one tooltip, you could add a "bool exclusive"
flag to the ActiveToolTip::showToolTip function, and then hide all
tooltips that have a lower priority when dealing with an 'exclusive'
tooltip.

Greetings, David