Update the event sample to define (as) many (as possible) event handlers for a
test button and log messages in all of the handlers to leave a trace of the
order in which they were executed.
Add a pointer to this feature of the event sample to the events overview.
Closes#11156.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61852 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775