Currently, some mechanical functions of an Element's Adorners make it significantly less efficient as a method to assign the Element to a Row/Column/Span than using the Properties Panel.

This friction occurs (in part) due to inefficiency across three main areas:

1) It is incredibly difficult from a motor skills perspective to get a positive 'snap' between an Element's edge and the Gridline that is attempted to be snapped to.

It usually takes me between 3-5 'jitters' of the mouse to feel confident that I snapped correctly.

--> To ease this, maybe we need to consider increasing the 'strength' of the snapping to make it less of a delicate task.

2) Using the Adorners wipes any previously-set 'Auto' measurements.

If an Element is assigned to a Grid Row/Column/Span, and set to a Height or Width of 'Auto', as soon as the Adorners are used to change the Row/Column/Span assignment, it replaces the user-set 'Auto' values with fixed-pixel dimensions, adding two extra steps (clearing local values) to the process of assigning an Element to a Grid area.

--> To resolve this, I would suggest keeping a memory if the Element had a previous 'Auto' value set, and retaining it IF when the moment the mouse is released, it has a positive snap to a Gridline. Without a positive snap, then the Width and/or Height would behave as it does currently, and directly interpret an adorner-drag as a straight Width or Height adjustment.

3) Using the Adorners adjusts an axis which is not included in the Element's manipulation.

For example, if using the horizontal Adorner to adjust the Width/Column/Span, not only will the Width value adjust (expected), but also the Height value will be changed.
This can be particualarly disruptive in a case where for example, the Horizontal is adjusted, but the Height, which was previously 'Auto' is then wiped and replaced with a new fixed-pixel value measurement.

--> To resolve this, I would suggest that we only change the property value of the axis being modified in the adorner. Changing the Horizontal should never affect the Height, and vice-versa with Width.