Delphi/Lazarus: Fully Expand or Collapse TreeView

Nothing is easier than that. You do not have to care about a function navigating through all items.

Just use

TreeView1.FullExpand; 

to unfold all branches and

TreeView1.FullCollapse;

to close all branches again.
2013-11-25 at 13:13

If you still want to use your Expand function, you can of course also do:

if TreeView1.Items[0] <> nil then
   TreeView1.Items[0].Expand(True);

Or:

if TreeView1.Items.GetFirstNode <> nil then 
   TreeView1.Items.GetFirstNode.Expand(True);

In case that the first item of the TreeView is set (otherwise there would be an exception), we are executing the Expand() operation on this first TreeView-Node. The "true" ensures that all other branches hanging on that node are expanded. If we pass "false", only the node is expanded, on which we have executed the Expand.
2013-11-26 at 22:08