Add the possibility to insert position markers into the scrollbar (like the "markers" feature in kate). I would suggest adding a contextmenu to the scrollbar draghandle (or middle mousebutton) to add a marker and when clicked I would show a little star in the scrollbar which can be removed using middleclick (or contextmenu).

Usecases:
1.) Tomcat startup of your favorite search engine (in this case lucene) - directly after startup it will do a complete reindex outputting every object it has indexed - there may be errors in between - and of course you want to fix those - so you have to scroll back to those errors - but there will be more when scrolling down - so I would just mark them in the scrollbar to be able to jump back and forth between those errors
2.) mark position where you started to install software xyz and where the password was generated and output for later reference

Reproducible: Always

Steps to Reproduce:
1. tail -f on Tomcat catalina.out, wait some time for logoutput to appear - meanwhile do some stuff in other konsole tabs
2. switch back to the tail-Tab and scroll back to quickly grasp whether there were any errors
3. each error I find I add a mark in the scrollbar
4. jump back and forth between those errors by clicking on the stars to compare if it is the same error