private void OnLeavePanel(DetachFromPanelEvent evt)
 {
     AddFromUrlFieldContainer.UnregisterCallback <FocusEvent>(OnContainerFocus);
     AddFromUrlFieldContainer.UnregisterCallback <FocusOutEvent>(OnContainerFocusOut);
     UrlTextField.Q("unity-text-input").UnregisterCallback <FocusEvent>(OnUrlTextFieldFocus);
     UrlTextField.Q("unity-text-input").UnregisterCallback <FocusOutEvent>(OnUrlTextFieldFocusOut);
     UrlTextField.UnregisterCallback <ChangeEvent <string> >(OnUrlTextFieldChange);
     UrlTextField.Q("unity-text-input").UnregisterCallback <KeyDownEvent>(OnKeyDownShortcut);
 }
 private void OnEnterPanel(AttachToPanelEvent evt)
 {
     AddFromUrlFieldContainer.RegisterCallback <FocusEvent>(OnContainerFocus);
     AddFromUrlFieldContainer.RegisterCallback <FocusOutEvent>(OnContainerFocusOut);
     UrlTextField.Q("unity-text-input").RegisterCallback <FocusEvent>(OnUrlTextFieldFocus);
     UrlTextField.Q("unity-text-input").RegisterCallback <FocusOutEvent>(OnUrlTextFieldFocusOut);
     UrlTextField.RegisterCallback <ChangeEvent <string> >(OnUrlTextFieldChange);
     UrlTextField.Q("unity-text-input").RegisterCallback <KeyDownEvent>(OnKeyDownShortcut);
     Hide();
 }