In the map direction thread, my answer has vanished, will try to repost. This thread I find in Living Room, while I thought it was a software question, but no problem. I am sorry, the Smartphone thread was here in "Living Room", so I myself, inadvertently, put this thread herein, so no chance to find it in the main category "General Software Discussion". So all my fault and my fault alone.
I opened up a second thread because I did not want to mix this general iOS/Android screen navigation issue with map navigation, and as said, I mainly think of navigation in web pages, it's absolutely correct that for maps, zooming in an zooming out would be best, and/or shifting the screen in any direction, but for web pages, most of the time, the smartphone PgDn equivalent is needed.
Thank you for mentioning Android macro apps, I'm not sure they can do what I want. After posting yesterday, I had a second thought.
First, I did not think of lefthanders. So this tap area of 1 cm2 should be in every screen corner, perhaps optionally right OR left or right AND left. Second, functionality would switch with landscape/portrait direction of the device, as with every other app for smartphones/tablets. Third, if the tap area is only 1 cm2 and square, it would be reasonable to have Home (top) and End (bottom) by 2 quick tabs, and PgUp/PgDn by single taps. Home and End being the equivalent to the pc keyboard keys, so Home/End would go to the start/end of the current page, and PgUp/Dn would shift by 1 screen length.
Perhaps I do not understand smartphone programming correctly but since those apps function with a sensitive/touch screen, and apps being independent from each other, I had thought that any tap on the screen could only reach that app which is directly under the pixels of that screen region, so if your browser app has the full screen, normally top layer, I wasn't aware that a second app could be, invisibly, be laid on top of the current app, but with the browser app, which is under it, second layer now, getting all other screen taps etc. notwithstanding, except for a cm2 in each corner, which should react to the macro app.
This evening, I spent several hours trying with Android emulators, Bluestacks, then Andy. According to Bluestacks, my graphics card was fine, but then, installation never went through, and Andy told me, again after downloading the whole program, that there was something wrong with my graphics card - I know that Android does graphics in another way than Windows.
So I was not able to try anything out, let alone scrolling by tapping, by lack of a touchscreen to begin with, but I had hoped I could perhaps mimic that with mouseclicks.
I am not sure I'll be happy with Android since I also need a database, or more correct, an sql database viewer, and here it seems there is better software available for the iPad - hence my unsuccessful tries to try Android at least on my pc, in order to decide upon the OS before buying.
I had hoped somebody already uses some additional app with their browser, for Home/End, PgUp/PgDn and thus could tell that it works, or even that this is possible with Android but not with iPad, or the other way round - by lack of special macro app or for technical reasons, so that such an app is not even possible here or there -, as to make my decision which OS to buy, for me.