Observation: if I'm on a line defining a 'linear' or 'ease' transition, and then simply mouse-over a control point handle in the inline-editor, then this condition fires true and the 'linear' or 'ease' attribute is replaced by an equivalent cubic-bezier() definition.

Basically, I'm not sure that this condition is sufficient to distinguish between a dragging state and just a simple mouse-over.  Having said that, given the other problems that could arise from tracking to track whether the mouse button is/was down elsewhere is worth addressing this behavior.

Long story short, probably not worth changing.