About GtkTreeView & GtkTreeSelection

[mili <milimeter 163 com>]

Hello, Everyone

1. I want to force my tree view select a row at any time as long as the view 
is not empty. When I delete a selected row with:
  gtk_tree_store_remove(tree_store,@iter);
There is no row selected. I did add such code after the above:
  gtk_tree_selection_select_iter(tree_selection,@iter);
But no use. So it's my first problem, how to force treeview always select a 
row even after delete the last selected row.

2. I have a lot of nodes in a tree, then I want to change all nodes from the 
5th till the end to be children of the 4th node. Or from one child till the 
last same-level child  to be sibling of its parent. And the same question, 
how can I move a node up his sibling, or move down his sibling?

Thank you very much.
mili