Yes, eventually shows the items. Not after.
No. The reason for forking the process that gives the data to the treeview, is to avoid unresponsiveness of the GUI.
But you'll have to look into it.
It is quite responsive if the system returns the data fast.
I think that the GUI and the searching should be separated/forked.
When listing something slow, like a network share with lots of folders/subfolders, the GUI is "not responsive".
Other than that, nice looking.