I just started using the desktop client, but I have been using the phone app for quite a long time now.
On the desktop, the most common way I get started is to CTRL+T for a blank tab and then middle-mouse click several pages. I then do CTRL+PgDwn to change tabs.
But because opening tabs this way puts the focus in the address/search bar, Page Down doesn’t work.
Offhand I can’t think of what functions Page Down would perform in the address/search bar, so I’d like Page Down to control the main page.