Visual design: only properties and hierarchy zones work

I am trying for the first time the ~Visual designer and I am having a peculiar problem.
I can see the interface (the area where to drag controls and the right area where i can see Components, hierarchy and properties zones), I can change properties and layout, but when i click in a control/widget to drag it, nothing happens :frowning:

Any solution?

Env: win xp, + eclipse