hit enter key repeatedly toworad bottom of window, cursor will sink under the page.
while hit enter twice or more, cursor still sinks.
when any printable character (e.g. 'a'), page will be scrolled up, and cursor will appear.
OK : printable characters. (a-z, 0-9, ', ", #, ..etc.) and whitespace(' ') will pass.
NG : enter, tab, and backspace.
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Desired Behavior: page will be scrolled.