When using numericupdown to expand/collapse treeView nodes. Why the collapse part is not working ?

Question

I have a treeView in my form1 designer. The treeView variable name is: treeViewMS1
When i'm running my program the treeView is automatic expanded to level 1:
Now if i click on the numericUpDown and change the value to 2 then:
So the expanded part is working fine when i change of the numericUpDown by one up the expanded is working fine.
Now when it's on level 2 and i change the numericUpDown back to value 1 that's level 1 instead get back to my first screenshot Expanded level 1 it's getting back to the root level 0.
and i want that the collapse part will move only one level back but it dosen't matter if i'm on expanded level 2 or 3 or 5 it will allways jump to 0 to the root.
This is the numericUpDown value changed event:
decimal oldValue;
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
if (numericUpDown1.Value > oldValue)
ExpandToLevel(treeViewMS1.Nodes, (int)numericUpDown1.Value);
else
CollapseToLevel(treeViewMS1.Nodes, (int)numericUpDown1.Value);
oldValue = numericUpDown1.Value;
ExpandToLevel method:
void ExpandToLevel(TreeNodeCollection nodes, int level)
if (level > 0)
foreach (TreeNode node in nodes)
node.Expand();
ExpandToLevel(node.Nodes, level -1);
And CollapseToLevel method:
void CollapseToLevel(TreeNodeCollection nodes, int level)
if (level > 0)
foreach (TreeNode node in nodes)
node.Collapse();
CollapseToLevel(node.Nodes, level - 1);

Answer 1

I solved it this way:
I solved it like this: In the Form1_Load event i did:
SetToLevel(treeViewMS1.Nodes, 1);
In my case i wanted it to begin by default in level 1.
Then in the numericupdown1 changed value event:
private void numericUpDown1_ValueChanged(object sender, EventArgs e)
SetToLevel(treeViewMS1.Nodes, (int)numericUpDown1.Value);
Then the method SetToLevel:
void SetToLevel(TreeNodeCollection nodes, int level)
foreach (TreeNode node in nodes)
node.Collapse(false);
ExpandToLevel(nodes, level);
And last the method EXpandToLevel:
void ExpandToLevel(TreeNodeCollection nodes, int level)
if (level > 0)
foreach (TreeNode node in nodes)
node.Expand();
ExpandToLevel(node.Nodes, level -1);
And now it's working perfect like i wanted it to work. When changing the numericupdown value it's changing the node tree expand/collapse levels.