Maybe something like this?...
 Code:
function treeView_Click()
	dim $checkedNodes, $i, $is
	for $i = 0 to $Form.Treeview1.Nodes.Count - 1
		if $Form.Treeview1.Nodes($i).checked
			$checkedNodes = $checkedNodes + $Form.Treeview1.Nodes($i).FullPath + @crlf
		endif
		for $is = 0 to $Form.Treeview1.Nodes($i).Nodes.Count - 1
			if $Form.Treeview1.Nodes($i).checked
				$Form.Treeview1.Nodes($i).Nodes($is).checked = 1
				$checkedNodes = $checkedNodes + $Form.Treeview1.Nodes($i).Nodes($is).FullPath + @crlf
			else
				$Form.Treeview1.Nodes($i).Nodes($is).checked = 0
			endif
		next
	next
	if $checkedNodes
		$Form.TextBox1.Text = $checkedNodes
	endif
endfunction