How much Text Movement Happens after PageUp or PageDown Keystrokes?

asked 2019-02-03 17:26:25 +0200

passer-domesticus gravatar image

updated 2019-02-03 17:28:10 +0200

I frequently use LibreOffice to read LO documents. Indeed, since I dislike wasting paper, I try to read them almost always on the screen.

When doing so, I page up or down using the PageUp and PageDown keys. However, every time I page up or down I have to search the continuation of the last line I just have read after scrolling.

In general I read to the last line displayed in LO's window to its end (sometimes even if the descenders may be cut off a bit. I do so as long as the line is easily readable, I don't mind if it does not impair readability). But after paging down, I frequently see myself searching the continuation of my last line after scrolling.

Of course, this could be improved by showing e.g. a thin colored – e.g. blue – line between the formerly last line on the screen and the next one which could not be displayed before. If such a mark would be present, I would search for this colored mark after paging down and continue reading immediately at the right place.

For paging up it would be advantageous to always display another such line between the topmost and the second topmost line. After paging up, one would see this line close to the bottom and continue reading in the right place searching this line.

Of course, every time the screen becomes scrolled by less than a page, e.g.

  • by the arrow up or the arrow down cursor key

  • or by continuing a line at the end of the displayed window past its end

  • or by running to the left on past the beginning in the uppermost displayed line

the auxiliary lines indicating the former relevant window top or bottom should also be updated. By the way, the amount of scrolling in these situations even seem to be part of some unknown algorithm (unknown to me, not to those who programmed it). Also, if I place the cursor with the mouse into the uppermost or lowermost line: There also seem to be some implicit scrolling of some defined amount (how much?).

Paging up or down might be done always such that these marks together with their adracent line to be displayed are always visible after paging up or down.

Right now I do not see the exact rule used internally when paging up or down using the dedicated keys. The rules associated with paging seem to be associated with the current insertion cursor. It seems to move this mark up or down (depending on page up or page down) a certain amount of lines.

I did not find out a rule for the horizontal position after page up or a page down movement. There might be no text at this position in the defined number of lines (or defined vertical distance?) above or below the current insertion pointer. And the insertion pointer is something not very eye-catching!

What are the rules governing

  1. the placement ...
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