show a visible change in the visible area of the Preview-tab

[ralf3u]

Conditions
1: In preview.conf: snippet_html=false
2: A very long html-document where on need to scroll in the Preview-tab and where there is in the editor a lot of text within one single p-tag.

Steps to reproduce
1: scroll with the scrollbars of the sidebar to the bottom of the web-page
2: add in the editor one letter at the beginning of the p-tag

Result:
The change is not in the visible area of the Preview-tab. To see the change one need to scroll in the Preview-tab to the top.

Possible solution
Geany Preview should do something like this: If the visible change is not in the visible area of the Preview-tab, then put the visible change in the visible area of the Preview-tab, if possible at the same level like the highlighted line.

Remark
What I mean with "show a visible change": Not all changes of the editor should be shown in the visible area of the Preview-tab, but changes in the Preview-tab that can be recognized by a person. So, for example if there is a long html-document and the user is adding at the very end of the document an empty div-tag, then Geany Preview should not execute "show a visible change in the visible area of the Preview-tab". Same for div-tags with visibility: hidden or display: none. If this is not possible to realize, then "show a change" is the alternative.