Can't scroll to the top or bottom of m y page in the editor

Editing
1

I have created a b asic html page. In the editor i can only see the middle section. The heading cannot be scrolled to. if I view the page in the browser it displays OK. PG v7.0.3 PRO Personal.

Any idea how to get to the top line? And why does the editor not behave like a browser?

Thanks!