When you click to edit a parameter, if there are more iterations than can be shown on the screen, the edit a parameter window isn't visible. This happens for example, when you have 12 iterations (like in a monthly breakdown).
The scroll bar doesn't work. Using the mouse wheel works to make it visible.
This happens with Google Chrome Version 33.0.1750.154 m.
In Firefox 26.0, the window is not visible. The scroll bar, or mouse wheel works to make it visible.
The window should be visible immediately when clicked rather than scrolling down to see it.