For Free positioning to work for normal topics, your preferences must allow it (Preferences → Advanced, check Allow Free Positioning) or you select that Modify → Allow Free Position (a check mark appears next to it).
When it comes to floating topics, free positioning allows you to a floating topic close to a normal topic so that it does not snap to a normal one. If you don't allow free positioning, a floating topic will snap to a normal one _unless_ you press shift while dragging.
I have Allow Free Positioning checked in the drop down and in Preferences. I'm holding the shift key down as I drag and my topics are still attaching one another when I try to move them. In the old version of X-Mind this worked. What's going on?