private void label1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e) { if (System.Windows.Forms.Control.MouseButtons == System.Windows.Forms.MouseButtons.Left) { //start dragDrop operation, MyDropTarget will be called when the cursor enters the AutoCAD view area. AcadApp.DoDragDrop(this, "Drag & drop successful!!!", System.Windows.Forms.DragDropEffects.All, new MyDropTarget()); } }