Like it says on the tin. ; ) Doubt this is fixed it 9.7, but we cannot upgrade (yet) as we are only demoing 9.5 and don't have permission to download 9.7 yet.
This wouldn't seem like a big deal except that a) some filename paths are so long in the Log File Viewer Source column, you can't scroll over far enough with the horizontal scroll bar in that window, and b) you can't rearrange the columns, either. You do get the little left/right split arrow when you hover over it though.
Also note: you *can* resize the columns when you first spawn a History window; it's only when you click on a log file in the History and open the Log File Viewer where it doesn't work. (eg - in the attached picture: red box, no good. Yellow box, works ok.).
I checked and tested this in DLO 9.7 and I am happy to report that you can adjust the size of the column in the log file viewer - see screenshot.
(you should be able to see that I adjusted some columns by making them smaller or larger, to show that every column is adjustable)
Re-arranging the columns is currently not possible.