I switched to the new layout for the desktop app and noticed that the message panel column takes up an unnecessary amount of space on the desktop app. I would like to be able to further narrow the left column (message panel). It eats up a huge amount of real estate that would be better used for center column with the actual conversation (see attached). The same problem exists on the web app.
I am only able to narrow it to about 1/3 of the overall screen - which is a total waste. I submitted a ticket about this (#18823765) and they said that there was nothing that could be done and suggested I should report it here too.
Please adjust the frames on this app for greater customization.