Question

Another similar StackOverflow question helped me up to a point.

My TableViewer cells contain boolean widget editors(not your usual check-button widget, but a toggling button, that can be “Checked”/”Unchecked”).

The table must:
– always show the editor when a cell is selected;
– disable the editor when cell focus is lost;
– properly move to the next row when TAB is pressed;

Apparently easy, hard in practice. A lot of listener conflicts (TAB doesn’t really work).

Later edit:

I’ve managed to solved the majority of bugs, but this one bug still boggles my mind. If I change the value of the widget with the mouse, then press TAB to traverse, the focus jumps to the second next row, not the next one. BUT if I change the value of the editor using space bar, then the traversing works just fine; it jumps to the next row as it should.

How should I debug those damn listeners?

Answer 1

For ease of development you can use some helper classes in JFace and you will not have to deal with the event handling of tabbing or mouse clicks. Here is a snippet that should help you get started:

TableViewer viewer = ...

TableViewerFocusCellManager focusCellManager = new TableViewerFocusCellManager(viewer, new FocusCellOwnerDrawHighlighter(viewer));

ColumnViewerEditorActivationStrategy activationSupport = new ColumnViewerEditorActivationStrategy(viewer) {
    protected boolean isEditorActivationEvent(ColumnViewerEditorActivationEvent event) {
        if (event.eventType == ColumnViewerEditorActivationEvent.MOUSE_CLICK_SELECTION) {
            EventObject source = event.sourceEvent;
            if (source instanceof MouseEvent && ((MouseEvent)source).button == 3)
                return false;
        }
        return super.isEditorActivationEvent(event) || (event.eventType == ColumnViewerEditorActivationEvent.KEY_PRESSED && event.keyCode == SWT.CR);
    }
};

TableViewerEditor.create(viewer, focusCellManager, activationSupport, ColumnViewerEditor.TABBING_HORIZONTAL | 
    ColumnViewerEditor.TABBING_MOVE_TO_ROW_NEIGHBOR | 
    ColumnViewerEditor.TABBING_VERTICAL |
    ColumnViewerEditor.KEYBOARD_ACTIVATION);