Bug 130854 [CellEditors] JFace TableViewer ignoring ICellEditor validator state
Using a validator on a TextCellEditor and entering invalid text into a cell results in ICellModifier.modify() being called with a null value, rather than an error being reported and the value being discarded. TableEditorImpl.saveEditorValue() *does actually check for editor validity*, but in the case of invalid values does nothing but no-op with comment "///Do what ???" and then calls cellEditor.getValue() which, for TextCellEditor's anyway, always returns null if its validator has invalidated the current value.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewerEditor.java
cancelEditing();
				}
			}
			
		};
		initCellEditorListener();
	}
	private void initCellEditorListener() {
		cellEditorListener = new ICellEditorListener() {
			public void editorValueChanged(boolean oldValidState,
					boolean newValidState) {
				
			}
			public void cancelEditor() {
				ColumnViewerEditor.this.cancelEditing();
			}
			public void applyEditorValue() {
				ColumnViewerEditor.this.applyEditorValue();
			}
		};
	}
	private boolean activateCellEditor(final ColumnViewerEditorActivationEvent activationEvent) {
		ViewerColumn part = viewer.getViewerColumn(cell.getColumnIndex());
		Object element = cell.getElement();
		if (part != null && part.getEditingSupport() != null
				&& part.getEditingSupport().canEdit(element)) {
			cellEditor = part.getEditingSupport().getCellEditor(element);
			if (cellEditor != null) {
				int timeout = cellEditor.getDoubleClickTimeout();
				final int activationTime;