I've had the problem in previous version and it continues in Adobe Extension Manager CC 184.108.40.206 (Mac), MacOS 10.10.2, that you can NOT adjust with width of the window, nor the Author column. Why not?
I know you can adjust the Name width, and the Version width, but if you try the Author, it looks like you can, but it never widens. You can NOT adjust the whole width of the app window at all. On top of that, any window sizing is completely lost once you quit. It will not open up as you have set things up.