Many changes:

Many changes:
- Introduced GTKGetWindow() which returns all GdkWindows associated with the
  given wxWindow
- Renamed IsOwnGtkWindow() to GTKIsOwnWindow() to avoid confusion with the old
  virtual function (the new one is non-virtual and is implemented in terms of
  GTKGetWindow())
- Refactored/simplified event handlers code in gtk/window.cpp
- Fixed some header guards names (__GTKFOO__ -> _WX_GTK_FOO_H_)
- Added GTKUpdateCursor() which sets the current cursor for all windows
  returned by GTKGetWindow()
- Factored out code from many different classes in wxControl::OnInternalIdle()
  which now updates the cursor, checks for internal focus and sends update UI
  events

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40816 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775