Hello,
I run Linux-Mint 18.2-KDE. One issue I have with the new release is that the little icon on the left bottom (Anwendungs-Starter in German) for selecting applications to run only functions correctly using its "full-screen" mode and not in the other two modes. More precisely - it only works as it did under Mint 17.3-KDE when preceding the click on it by clicking on the mini-program selection icon for displaying the workspace itself. I wonder whether this behaviour is "works as designed" or a bug.
Regards
H. Stoellinger

Sounds like Mint chose the application dashboard over the standard application launcher or Lancelot. Try a different starter widget to suit your needs.

HTH.

Thanks for the quick answer, toad; is there an easy way to activate a different starter?

Click on the three bars on the panel, select "add widgets", click on the funnel and select "application launcher widgets". Add them all to your panel to see which one you like best and then remove the others you don't like.