I cannot control navWinSize

[jpereiranet]

Hello:

My problem is around the size of navigation window. With some images, the navigation window is too big. I am trying control them with the navWinSize parameter, but seems not run. If I set navWinSize to 0.2, 0.1, 0.9 or 20 nothing changes.

I attached a screenshot:

Where is my problem?

Thanks a lot!