[NFBCS] NVDA add-on Developer toolkit and overlap detection

[Andy Borka]

  Hi,

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?