How to listen to lose focus event of a part in Ecl

Question

I have multiple views in a perspective, these are shown as tabs. I want to catch the event when I switch from one Part to another (by clicking on the other parts tab). In other words I want to catch the event when a part looses focus. How can I do that in E4?

I have tried IPartListener implementation but its methods are called twice and also too late. For example, if I have parts A and B and part A is in focus, when I click on tab for part B, the @Focus method of part B is called first and then part deactivated (or part hidden) method of IPartListener is called for part A. I do not want that. Also, I have noticed that the partActivated and partDeactivated methods are called twice (for each part), which is also not desireable.

Any help would be greatly appreciated.

Thanks, Jehan