I can group objects into a Pool by SHIFT-dragging them onto it. If I then drag the object above the current border of the Pool, the Pool will automatically resize.
However I could not figure out how to group an Object into a single Cell or even a Row or Lane. E.g. I have a BPMN Start Event that I want to be 'stuck' inside the Cell of Column 0, Row 2. Obviously I can position it there myself, but as soon as I use any automatic Layout like e.g. Flowchart or BPMN it will often times reposition the Start Event to another Lane.
What am I doing wrong?