Executing several decision tasks in one step

[Márton Zsolt]

Hi all,
We are in 4.6c (before an ECC 6.0 upgrade).
One of our users receives several decisions tasks and she wants to execute in one step. 
I know, that this is possible, but I cant realise how...
Selecting the tasks and executing them the system opens each step one by one. 
If I'm right the decision task must be shown just once and after that in a popup window I can choose, if I would like to execute the selected tasks in the same way.
Are there any settings regarding this, or what am I doing wrong?

Thanks in advance
Zsolt