Bug 201906 [Viewers] 3.4 ColumnViewerEditor leaks ViewerCell instances.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewerEditor.java
}
	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();
			}
		};
	}
	void activateCellEditor(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;
				if (timeout != 0) {
					activationTime = activationEvent.time + timeout;
				} else {
					activationTime = 0;
				}
				if (editorActivationListener != null