I noticed that I can drag-and-drop a bunch of stuff from the Project Editor to a microflow: import and export mappings, other microflows, pages. This helps me go fast when developing.
However, when I try to drag-and-drop a Rule, it does not accept it. Currently, if I want to use a rule, I need to create a new decision action, select Rule radio button, and then find the name of the Rule. This slows me down.
I checked this behaviour on a recent Mendix version of 9.10.0, and it does not support drag-and-drop of Rules into microflows.