[KDE] Somehow rekonq [and konqueror] opens a new windows instead of a new tab

[AlmaTlust]

Hi,
every time I use krunner to google (or whatever) something, rekonq is started in a new window. When I click on an html link in kontact, the same. I set rekonq to open external links as new tab, but it does not work. Can someone give me a hint? Thanks a lot!