Hi Eshar,

Most of our UI controls has Property Renderer which is responsible for the control's drawing.

In your case to make some custom drawing you should create renderer class that inherits from NTreeViewExRenderer (NTreeList is a child class of NTreeViexEx control so NTreeList use NTreeViewExRenderer as a renderer) and override some of its methods.

For example you can override PaintBackground and add your drawing in it.

public class MyNTreeViewExRenderer : NTreeViewExRenderer
{
    public override bool PaintBackground(NTreeNode node, NTreeViewExPaintContext context)
    {
        //Do your drwawing using context.Graphics. ...
        return base.PaintBackground(node, context);
    }
}

Then you should set an instance of this class to the NTreeList.Renderer.

In this case to be able to view your custom drawing you should have at least one node in your NTreeList.

Best Regards,
Nevron Support Team