Can't reduce size of expanded notes field

Just used the feature to expand the notes field, but I made it TOO big, but I can't seem to reduce the size.

When I mouseover the Notes field’s bottom bar, I see the cursor change, but I can not drag up to reduce the size of the field. Instead I simply highlight contents inside the notes field.

Help! Now the open item window is too big for my screen, and it is hard to access the buttons OK and Cancel at the bottom of the window.