Bug 189847 [DND] Combo/Text on Linux does not fire Drop event.
examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/dnd/DNDExample.java
dropControlType = c.getSelectionIndex(); 
			dropControl = createWidget(dropControlType, parent, "Drop Target");
			dropControl.setLayoutData(data);
			if (dropEnabled) createDropTarget();
			parent.layout();
		}
	});
	
	Button b = new Button(parent, SWT.CHECK);
	b.setText("DropTarget");
	b.addSelectionListener(new SelectionAdapter() {
		public void widgetSelected(SelectionEvent e) {
			Button b = (Button)e.widget;
			dropEnabled = b.getSelection();
			if (dropEnabled) {
				createDropTarget();
			} else {
				if (dropTarget != null){
					dropTarget.dispose();
				}
				dropTarget = null;
			}
		}
	});
	
	b.setSelection(true);
	dropEnabled = true;
	
	FormData data = new FormData();
	data.top = new FormAttachment(0, 10);