Selecting a value from a SWT CCombo on RCP

It looks like the CCombo custom SWT object lacks some selection functionality. When using a CCombo as a table cell editor on a Rich Client Platform (RCP) application, it is (almost) impossible to detect the user selection with both the keyboard and the mouse.

The selection listener does not work as expected. Documentation says:

  • the widgetSelected method is triggered whenever a selection occurs in the control, i.e. when the user browses the option list this event is triggered;
  • the widgetDefaultSelected method is triggered when default selection occurs in the control, i.e. when the user selects an option from the list this event is triggered.

One might think that all one has to do is to catch the widgetDefaultSelected event and one would know which option the user has selected from the list.
This is only true when the user performs the selection using the keyboard, i. e. after browsing through the options list the Enter/Return key is pressed.
If the user decides to use the mouse, the widgetDefaultSelected event is not triggered at all, but widgetSelected is.

One may though one could detect the user selection with the mouse listener. But it turns out there’s no (easy) way to detect if the user has performed a selection using the mouse…

Here’s a workaround for it. Since the widgetSelected is triggered by the mouse clicks, one may think in trying to use that event. Unfortunately the event has no real useful information, like if it was triggered by a right button mouse click. But fortunately, the CCombo object does have a couple of methods that allows to infer that a selection has been made. In particular, it has a method to check if the options list is visible or not. Since a selection with the mouse makes the options list disappear, one can use it.

Here’s a code snippet that does it:

// Selections events
combo.addSelectionListener(new SelectionAdapter() {
// Selection changed, check if the options are still visible
public void widgetSelected(SelectionEvent e) {
  // If list is not visible assume that the user has
  // performed selection with the mouse
  if (!combo.getListVisible()) {

// Option selected
public void widgetDefaultSelected(SelectionEvent e) {
  // User performed a selection with the keyboard

This is not a perfect solution, it’s a workaround, but it’s a very helpful working solution.