private void OnLeavePanel(DetachFromPanelEvent evt)
{
SearchTextField.visualInput.UnregisterCallback <FocusEvent>(OnSearchTextFieldFocus);
SearchTextField.visualInput.UnregisterCallback <FocusOutEvent>(OnSearchTextFieldFocusOut);
SearchTextField.UnregisterCallback <ChangeEvent <string> >(OnSearchTextFieldChange);
SearchTextField.visualInput.UnregisterCallback <KeyDownEvent>(OnKeyDownShortcut);
}