add a rezise bar to adjust size of thing in schedule

I have an ultra large screen. as you can see when i’m in full screen there is a lot of loose space. I would like to be able to adjust the size of the side pannel to be able to see more of the gant chart. I know that I cant close the side panel but I would prefer to resize it so I can see it while adjusting the chart. or maybe individualy adjust each colum size