On Mac: opening Library and resizing has unusual ratio of panes

When I use a key command to open the floating Library, it does remember my last window/pane locations. However, when I widen the window, it always makes the Filter pane unreasonably wide. Most Mac apps do not operate in this way. They are just wide enough, and then the rest of the pane expands. I see that it is following a ratio, but beyond a certain point it is not helpful. It's been this way for a long time, but today it just finally made me take action...

I'm usually making it wider so I can see more columns in the right pane.

Here is a video of how it flexes the panes:

https://www.dropbox.com/s/0aqmqsp5mp5cn7n/Logos_8_Mac-pane-expand.mov?dl=0