What version are you running?
1.6.9
What's the URL of the page this enhancement relates to, if any?
http://reviewboard.dev.ubiquisys.local/r/4123/
Describe the enhancement and the motivation for it.
if you are seeing the diff between 2 files , you should atleast show complete C function () by default in which code changes are done this is very much needed to get the complete context , you just mention the function name which is not enough , and expend option prvided usually shows huge no of lines if file size is big then this sometime shows more than 10K lines , if you just give an option to view the complete C function () would be great.

Also when you viewing the code diff , there should be navigation buttons to go to the Next diff , i have to use the scrollbar to see the next difference this is very inconvenient , this becomes worst if i have to expend the code . 
What operating system are you using? What browser?
Windows , Chrom . 
Please provide any additional information below.
if one submitter wants to submit multiple review , the second review should show only delta difference between first review and second review , this will help reviewer to track the code changes against the comments given in first review .