Feng,
I think that what you are asking is possible and we can create a little sample app to show that. But first, I need to make sure I understand well your requirements:
-On the map, there are aircraft moving around based on their updated position.
-Each aircraft is represented by an icon
-Each aircraft has a label with two column values on two lines. There is a line between the label and the icon to avoid confusion on what label belongs to what icon if the icons are close together.
-On aircraft can be selected by clicking either on its icon or its label
-When the aircraft is selected, the icon and label are showed differently and the label shows more info from additional columns (extended).
-The label can be dragged to change its position relative to the icon with the line still there to show the relation with the icon
-As the aircraft moves, the label keeps moving too relative to the icon.
Can you confirm us this is what you are expecting? Thank you.