Stuck in Viveza's "negative" mode

When positioning a control point, I usually use the negative (inverted b&w) display to get the effect exactly where I want it. I do slide point or point’s sliders. I’m likin’ this!

But… sometimes, after releasing the key, the screen doesn’t go back the original “positive” state.

In the control point list, there’s a check box that invokes a control point in “negative b&w” and holds it there without using the key. Fine - I use it occasionally. No problem there.

The problem is that sometimes that box is checked without my doing it. At some point in sliding a control point, it latches to “negative b&w”; the check box is checked without my permission.

Is this a feature or bug?