Path Editing tips for adjusting tangents using the March CTP of  Microsoft Expression Interactive Designer:

 

Adjusting tangents using the sub select tool:

 

Clicking and dragging tangents with the sub select tool:

Clicking and dragging a tangent adorner will also adjust the direction of the adjacent tangent if and only if the two tangents lie in opposite directions (within 0.25 degrees) when the mouse button is first pressed.  If the two tangents are not lined up when the mouse goes down, the adjacent tangent will not be changed.  Thus, if you drag a tangent at a sharp corner, only one tangent moves; if you drag a tangent at a smooth point, both tangents move. 

How to adjust adjacent tangents equally in size and direction with the sub select tool:

Press alt and hover over a point, then click & drag.

How to change a tangent independently of its adjacent tangent using the sub select tool:

Press alt and hover over the tangent adorner, then click and drag the tangent adorner.
The clicked side of the tangent will change in both size and direction independently of the other side.

 

Adjusting Tangents using the pen tool:


How to adjust adjacent tangents equally in size and direction with the pen tool activated:

Press alt and hover over a point, then click & drag.

How to change a tangent independently of its adjacent tangent using the pen tool:

Press alt and hover over the tangent adorner, then click and drag the tangent adorner.
The clicked side of the tangent will change in both size and direction independently of the other side.

 

The pen tool cannot be used to click or drag tangents (without modifier keys such as the alt key).