I asked for the same option years ago :) It's not possible, you can do a sort for an application with a click if you wish. I use Ctrl+Right click for this. I set it in advanced options as below (the last one):

Rolf,

You've done it right, but may be you have the wrong version. That option is available in the beta version v5.3.0.1. You can download it from http://rammichael.com/7-taskbar-tweaker file named 7tt_setup_beta.exe.

After that, you just need to hold the Ctrl key and right click on the taskbar item. It will do the same thing as "Sort group items".

Awesome! Better than what I asked for :) Thank you very much!

I assigned taskbaritem|ctrl+rclick to 15, so I can sort any application easily.

@RaMMicHaeL, is it possible to automate sorting with a Mouse Button Control in Advanced Options? For example, when I double click on emptyspace on taskbar, I would like a certain application's windows to be sorted. If not possible, sorting all applications would also help.