Hi Irene, have you tried achieving this with Menus widget? Going by the above screenshot, you can simply use Menu widget and each menu item could correspond to particular Mashup containing different visualisation.
Feel free to correct me if I got your use case wrong.
Thank you very much for your response. Ten minutes after posting this discussion, I found a post that gave me this very same idea. I tried to delete this post but I couldn't .
You are right and it is actually quite simple, just create a menu with the mashup you want to access to. In the mashup, drag and drop a menu widget and a mashup container and bind the menu to the mashup container: