Author: Tim Kosse <tim.kosse@filezilla-project.org>
Date: Sat Aug 26 15:37:30 2017 +0200
If a wxTopLevelWindow has been instanced, but Create has not been called, calling Destroy on the window results in an assertion in Show(false), at least under wxGTK. Fix this by only hiding a top level window during destruction if it is actually shown.