Hi Catalin,
I regret for the inconvenience caused in the delay in getting back to you on this issue. You can try the below code to access the image index in the image list and trace the image that you are looking for.
I have used the TreeView MouseUp event and got the SelectedNode for this operation.
[C#]
private void treeViewAdv1_MouseUp(object sender, MouseEventArgs e)
{
int _index = this.treeViewAdv1.SelectedNode.LeftImageIndices[0];
this.pictureBox1.Image = this.imageList1.Images[_index] as Image;
}
[Sample]
http://websamples.syncfusion.com/samples/Tools.Windows/F70225/main.htmPlease try this and let me know if this helps.
Regards,
Nanda