Lag when scrolling via keyboard

When lifting an arrow key after holding it down, the scrolling effect still keeps continuing.

How to reproduce:

Paste

(define (fact n)
  (cond
    [(zero? n) 1]
    [else (* (fact (sub1 n)) n)]))

to DrRacket over and over again until it reaches 150 lines.

Go to the first line, and hold the down key. Once the scroll bar is at 50%, lift the key. Notice that the page still keeps scrolling until it's at 75%. Also notice that initially, the line number at the bottom right will update instantly as the cursor is moving. However, once the page starts to scroll, the line number stops updating, and after scrolling effect ends, the line number suddenly jumps to the current line number.

This problem occurs with up, page down, and page up keys as well, though to reproduce the page up and page down keys issue, you might want to add even more lines to the file.

Racket 7.6 BC, OS X (Catalina)

Start by reproducing the issue in DrRacket with a long file and the arrow, Page Up, and Page Down keys as described. Trace the desktop editor's keyboard scrolling and line-number update handling; done means scrolling stops when the key is released and the line number remains current during scrolling.