Sometimes a panel will open so tall that even if you can drag the top of it to the top of your screen, you can't select the bottom edge so you can shorten it.
There is a "Reset" option for your workspace, but I don't think Adobe should assume users know about it or have to resort to it. To compare, my Mac and Windows computers can detect available resolutions and refresh rates of external displays, so it would not be a stretch to assume that a desktop application can detect the user's display and correct accordingly.