These should be initialized to deterministic values so it's easier to
catch improper behavior, as it'll always be reproducable, instead of
performing uninitialized reads.
These are only used within this class, so we can make them private to
keep their use contained. This also gets rid of the pre-Qt5 'slot'
identifier, since Qt 5's connection syntax doesn't require a function to
be declared a slot anymore.
Lioncash
Zach Hilman
James Rowe