private void OnLeavePanel(DetachFromPanelEvent evt)
 {
     SearchTextField.Q("unity-text-input").UnregisterCallback <FocusEvent>(OnSearchTextFieldFocus);
     SearchTextField.Q("unity-text-input").UnregisterCallback <FocusOutEvent>(OnSearchTextFieldFocusOut);
     SearchTextField.UnregisterCallback <ChangeEvent <string> >(OnSearchTextFieldChange);
     SearchTextField.Q("unity-text-input").UnregisterCallback <KeyDownEvent>(OnKeyDownShortcut);
 }
 private void OnEnterPanel(AttachToPanelEvent evt)
 {
     SearchTextField.Q("unity-text-input").RegisterCallback <FocusEvent>(OnSearchTextFieldFocus);
     SearchTextField.Q("unity-text-input").RegisterCallback <FocusOutEvent>(OnSearchTextFieldFocusOut);
     SearchTextField.RegisterCallback <ChangeEvent <string> >(OnSearchTextFieldChange);
     SearchTextField.Q("unity-text-input").RegisterCallback <KeyDownEvent>(OnKeyDownShortcut);
 }