* When hiding a wxWindow make sure that none of its subviews are the first

*   When hiding a wxWindow make sure that none of its subviews are the first
    responder.  If one of them is, make it resign. If it refuses, don't hide
    the window and return false.
*   When showing a wxWindow that has been hidden, schedule a reconfiguration
    of the key-view loop so that tabbing will work correctly.
*   Add some comments about why wxCocoa does what it does.

This makes the widgets sample much more usable.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52099 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775