Well, in my graph, I want to show something else, so for example, the expression would be 'electrical consumption' over dimension 'time'. So to answer Jagan, I would more have something like:
(just to know that 1 for B or C are not the same than for A). But this is only for the choice of graphs. Thus, if I previously choose building A, I will have 3 graphs, 1, 2 and 3. Etc.
Hope that's clear enough.
What i got from your explaination is:
1. You can just use getselectedcount(Building)>0 in the layout condition of container which would make the container visible when a building is clicked.
2. Then just create a combo inside the container having Building in the dimension and No. of Rooms in the Expression.
Hope this would help you.