NVDA add-on Developer toolkit and overlap detection

Andy B.


I am planning out a feature called overlap detection. However, I need your input on the matter. Since Developer toolkit has many different use cases and environments it works in, this feature may be difficult to satisfy in every scenario. In web content, CSS/HTML rules usually dictate that a child-parent relationship between two or more objects is permanent. In most cases, a parent object will grow to accommodate the combined size of its children. In other cases, such as the position: absolute or position: fixed style rules, the children of the parent can be truncated if it exceeds the parent's boundaries. In the position: fixed scenario, the objects in the position:fixed will at some point create an overlap because the object with the fixed rule maintains its original position, even if the page scrolls.
In other environments, the parent-child relationship doesn't exist, or the parent fails to accommodate the children's size. Thus, the child can exceed the boundaries of the parent. Developer toolkit can reasonably meet most overlap detection requirements, but I need some input on what reasonable guidelines to follow. What do you recommend?