private void treeView1_MouseDoubleClick(object sender, MouseEventArgs e) { if (treeView1.SelectedNode.Tag is Material) { frmMatEditor matEdit = new frmMatEditor(); matEdit.Init(); matEdit.Material = (Material)treeView1.SelectedNode.Tag; matEdit.Show(); if (matEdit.DialogResult == DialogResult.OK) { treeView1.SelectedNode.Tag = matEdit.Material; } } }