I still have to check what I'm selecting. I think it's required if you want select only certain features through filtering (face, body, line, point, etc...)
Here's what I'm doing with it:
public Component2 SelectedComponent()
// make sure we're selecting components
// this is required so I can check if it's a component or a face.
// without this I couldn't calculate lengths, or get custom info
swSelectType_e selType =
// are the components selected from the feature manager tree? Are faces selected
// from the assembly?
if (selType == swSelectType_e.swSelFACES)
// a face is an entity. need to convert it to a component
Entity swEntity = (Entity)mSwSelMgr.GetSelectedObject6(1, -1);
swCom = (Component2)swEntity.GetComponent();
else // no need to convert to a component
swCom = (Component2)mSwSelMgr.GetSelectedObject6(1, -1);