[FlipView] Fixed faulty 'status' detection for the control buttons.
[FlipView] Calling HideControlButtons overrides their visibility which is set by the FlipView internally.
[FlipView] Fixed a null reference exception in DetectControlButtonsStatus().
[FlipView] Adjusted the FlipView's banner opacity.
Merge pull request #499 from Amrykid/flipview-patch3

FlipView Patch #3