How to reset a ctk.ctkComboBox?

How to reset a ctk.ctkComboBox to index=0?

就是说, 一个ctk.ctkComboBox改变时,另一个 ctk.ctkComboBox恢复到index=0…

In other words, when a ctk.ctkComboBox is changed, another ctk.ctkComboBox is restored(or reset) to index=0…

@lassoan@Juicy@jamesobutler @jcfr @pieper