manual/advanced_topics/viewports/grayscale-conditional.tex

\begin{example}
    %?C<%Vda|%Vdb>
    %Vl|a|10|10|50|50|-|-|-|
    %Cl|0|0|50|50|
    %C
    %Vl|a|0|70|70|14|1|-|-|
    %s%acThere you have it: Album art.
    %Vl|b|20|14|50|14|1|2|-|
    %t1%acWarning:;%t.1 
    %Vl|b|20|30|50|50|1|-|-|
    %sNo album art found
    %scheck your filenames.
\end{example}
This example checks for album art. Album art will be displayed in viewport 'a', if
it is found. Otherwise a flashing warning will be displayed in viewport 'b'.