Selecting many items to move within the grid using keyboard -- I can no longer see where they are in the grid and am unable to move them to become sub-items of a same-level item (without using the mouse to find their location).

Select items that together are higher than the height of the window. (Let's number them 1 to 20, top to bottom.)

Move them up using Alt + arrow keys. (My goal is to make them sub-items of an existing item.)