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
newTypes[dropTypes.length] = transfer;
	dropTypes = newTypes;
	if (dropTarget != null) {
		dropTarget.setTransfer(dropTypes);
	}
}
private void createDragOperations(Composite parent) {
	parent.setLayout(new RowLayout(SWT.VERTICAL));
	final Button moveButton = new Button(parent, SWT.CHECK);
	moveButton.setText("DND.DROP_MOVE");
	moveButton.addSelectionListener(new SelectionAdapter() {
		public void widgetSelected(SelectionEvent e) {
			Button b = (Button)e.widget;
			if (b.getSelection()) {
				dragOperation |= DND.DROP_MOVE;			
			} else {
				dragOperation = dragOperation &~DND.DROP_MOVE;
				if (dragOperation == 0) {
					dragOperation = DND.DROP_MOVE;
					moveButton.setSelection(true);
				}
			}
			if (dragEnabled) {
				createDragSource();
			}
		}
	});
	
	Button copyButton = new Button(parent, SWT.CHECK);
	copyButton.setText("DND.DROP_COPY");