Data is not loaded immediately after import

[martijn]

As reported by Eugene van Someren:

When you've imported a dataset and changed the visualization settings nothing seems to happen or you get grey boxes. The remedy is simply to reopen the pathway. Obviously, it would be nice if this would not be necessary, but more importantly, it would be very helpful if this was mentioned in the tutorial text, to avoid frustration among new users.

[martijn]

I can't reproduce this problem.