PositionList Dlg: suppress two more warnings

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14559 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
PositionLIst Dlg: made it look more like the main frame.  Simplified layout code.

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14560 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd