always use wxSTAY_ON_TOP (closes #10447)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58679 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/busyinfo.h

@@ -48,6 +48,9 @@
     wxApp::Yield for more details). The simplest way to do it is to use
     wxWindowDisabler class as illustrated in the above example.
 
+    Note that a wxBusyInfo is always built with the @c wxSTAY_ON_TOP window style
+    (see wxFrame window styles for more info).
+
     @library{wxcore}
     @category{cmndlg}
 */