Addresses:
printf-format warinigs
indentation/style
unused variable warnings
used wxID_ABOUT for about menu entry
removed references to "minimal sample" in other samples
some other misc warinigs
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@16339 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
and checked for NULL in one of the event handlers, since
on the Mac the event handler may be called before the
control is properly initialized
Tested for an empty string in Mac's textctrl.cpp
else we get a crash if there is nothing in the text control
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15555 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
