Page-down unusual behavior

[WhiteNoiseDev]

I notice that Page-up/Page-down has an unusual behavior for a text editor.

Go To https://codemirror.net/6/ and paste a long text. Press Page Down
The cursor moves to line 11 and page is scrolled down by 1 line.

On CM5, the same action moves the cursor to line 11 AND scrolls the page to line 11.

For reference, VScode moves to the last line in view (10) and doesn't scroll the page at all.

I find CM5 or VScode behavior preferable to the current 1 line scroll.

Thanks for your work.

[marijnh]

Attached patch should address this.