Cancel-on-Close vs OK-on-Close

If I open one of the new Binding Detail windows and make changes, those changes are reflected immediately (in the underlying list view) and are retained if I close the window with the [X] in the upper right.

However …

If I open the Timing Detail sub-window for a binding, make changes, and click [X] on that window, it acts as a [Cancel]. I must click [OK] to save my changes.

I’ve hit this a number of times and lost my changes. I think its because the Binding Detail window has no [OK] / [Cancel] buttons and I’ve gotten in the habit of using [X].