Detach is not the same as “we stopped listening”
“We stopped listening” is a sentence we hear in walkthroughs. It usually means a component is no longer on the page. It does not mean the handler was removed.
In applications that change view without a full reload, a scroll listener attached in a widget can outlive the widget. The person using the application has moved to a quieter screen. The listener is still on the window. A second visit to the widget attaches a second handler. By late afternoon the page feels thick, and the complaint arrives as “the application is slow,” which is true and unhelpful.
In inventory work we mark attach and detach as a pair. An attach without a detach is not automatically a fault — some listeners belong on the window for the life of the visit — but it is a fact that should be written down. The flagship analysis then asks whether that fact explains the complaint. If you only remove the widget in the design file, you have not stopped listening. You have stopped drawing the widget.