Not sure if this is a DiffMerge issue....Most of the time I want to run DiffMerge from a command line (I use a Mac, so I'm launching /Applications/DiffMerge.app/Contents/MacOS/DiffMerge via an alias). However, when I do this DiffMerge does not get window focus, so I have to either click the window or Cmd-tab to it. Is there a way around this? Thanks.

Are you using the 'open' command with that? If not, try that. It should keep focus on what you launched when you use that commend.

You could also try an AppleScript to bring it to the front.

For example:

/Applications/DiffMerge/Contents/MacOS/DiffMerge.app &
/usr/bin/osascript
tell application "DiffMerge"
activate
end tell