Assume you have a TreeView, Docked 'Right on a Main Form.
You make sure all TreeNodes are expanded in the Form Load EventHandler:
private void Form1_Load(object sender, EventArgs e)
And, you force all its nodes to remain
expanded by using this BeforeExpand EventHandler:
private void treeView1_BeforeCollapse(object sender, TreeViewCancelEventArgs e)
e.Cancel = true;
At that point you need to define what you want to do when a TreeNode, or TreeNodes, is/are clicked, or selected.
To help you with that, we need to know more details: will clicking each TreeNode ... no matter what level they are at in the TreeView ... trigger the display of some other
Form, or of some container Control, like a Panel, inside the same form
the TreeView is on ? Is multiple-selection allowed: if so, what happens if there is a multiple-selection ?