How to control the folder node expand and collapse

Hi all,

I have a custom project with MPF for vs2012, and I hide a file node in the folder B.

When I double click the folder B, editor will load the hidden node. it works.

when the  folder Bis expanded, I double click the folder B, editor still load the hidden node, but the  folder B will collapse.

Otherwise, when the hidden node`s editor get focus, the folder B will expand.

I hope to keep the folder B expanded/collapsed.

Can anybody tell me how to implement this?

VSX