Another good comparing/merging tool is WinMerge. http://winmerge.org/

I guess it would be easiest for you if you would 
- somewhere allow to define an external tool for merging. 
- allow a shortcut to be set to call the merger tool, or a button in the text
diff view/tab.
- update the content of the files automatically when the tool is done, or at
least ask.

I do not know how it would be easiest done to select three files, but I guess it
would be a great start if at least two files could be opened automatically in
any of these external tools from within pspad.

-- 
<http://forum.pspad.com/read.php?2,64632,64778>
PSPad freeware editor http://www.pspad.com

Odpovedet emailem