InfoPath Dev

i tried doing it using conditional formatting. Used multiple combo boxes and have hidden them if the condition is false. but this results in a flicker in my repeating section. The moment i insert a repeating section, it expands and contract. This is beceause first it loads all the combo boxes then checks for the condition and then hides it. ...

I have two combo boxes. Values in one are based on the selection made in another combo box. The values for both the combo boxes is entered using combo box properties. and no external data source. How can i filter the data appearing in the second combo box based on the selection made in first combo box in infopath 2007.