Issue
... or perhaps a way to launch NetBeans through a middle-man app and open up a BASE and LOCAL file in the DIFF editor ...
Solution
If it is the style of the netbeans diff tool that you like, have a look at the free Perforce Merge Tool.
(source: perforce.com)
In TortoiseSVN settings set the external diff viewer to:
C:\Program Files\Perforce\P4Merge.exe -dw %base %mine
Answered By - Alistair Sutherland