flag running title and runningauthors if they are really too wide

[kmccurley]

At present we have just a warning if the title appears to be too long if it appears to be at least 70 characters, but this is just a guess. As it turns out, we can measure the exact width of the rendered title with something like this:

\newdimen\maxtitlewidth                                                                                                        
\newbox\measuretitle                                                                                                           
\maxtitlewidth=\textwidth                                                                                                      
\advance\maxtitlewidth by -15pt % allow for approximately two-digit page number width                                                              
\global\setbox\measuretitle=\hbox{\@IACR@title@running}                                                                        
\ifdim\wd\measuretitle>\maxtitlewidth                                                                                          
     \ClassError{iacrcc}{Title is too long for running head. Please use the running argument on \title with a shortened title.}                          
\fi                                                                                                                            

[kmccurley]

I forgot to mention that llncs does this.

[jwbos]

Very nice improvement: let's implement this!