Rectangle around the note head

[Matevz Jekovec]

I was searching the documentation a bit for a feature which draws a 
rectangle around the certain note head (or streched around 2 notes when 
punctuated over the bar). We use this kind of arrangement, to mark a 
note that is the highest in the line (the melody climax) in our 
contrapunkt class and I think this has become a standard for all the 
contrapunkt classes around. Can anyone help me out?
I'm sure you're way too busy with other lilypond features, so if this 
marginal feature is not already possible or there is too much work to 
implement it, I really apologize for your time.


Best regards!
- Matevz Jekovec
 a Slovenian music student