instead of taking time to trick the system , please take time to show us what you did ..
my solution as im like most of the others wont go around and download the plugin and try , will be doing so ..
$(function(){
$('.link-to-fullscreen').click(function(){
$('.wmd-panel').css({'width':'100%'});
})
})
put it under the code for the plugin ! and play around with the values and you should get the result that you want ..