Bug 49826 Type filter ignores some filters
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/TypeFilterPreferencePage.java
private boolean canEdit(ListDialogField field) {
			return field.getSelectedElements().size() == 1;
		}
        public void customButtonPressed(ListDialogField field, int index) {
        	doButtonPressed(index);
        }
        public void selectionChanged(ListDialogField field) {
			fFilterListField.enableButton(IDX_EDIT, canEdit(field));
        }
        public void dialogFieldChanged(DialogField field) {
        }
        
        public void doubleClicked(ListDialogField field) {