The Default Tray takes 50% of my screen and it does not let me resize when dragging the left or the right edge. Double clicking and re-sizing also does not work. The size remains fixed. I managed to drag the bottom edge upwards, but that’s as far as it allowed me to do.
Have you tried, View/Restore Default Workspace ?
Solved 
thanks for this tip, it worked.
Not working for me. Preferences/Workspace/Reset Workspace, rt? I had tried this and not working.