Provide more information for failures involving FindFocus()

It is useful to know where the focus actually is when a test checking
that it's set to a particular window fails.

tests/controls/searchctrltest.cpp

@@ -20,6 +20,8 @@
 
 #include "wx/srchctrl.h"
 
+#include "testwindow.h"
+
 class SearchCtrlTestCase
 {
 public:
@@ -45,7 +47,7 @@ protected:
 SEARCH_CTRL_TEST_CASE("wxSearchCtrl::Focus", "[wxSearchCtrl][focus]")
 {
     m_search->SetFocus();
-    CHECK( m_search->HasFocus() );
+    CHECK_FOCUS_IS( m_search );
 }
 #endif // !__WXOSX__