Overlay is overly dressed up with various distracting items. It is overused for all admin items.
Simplify the overlay for more focused short interactions. See #1882482: [meta] Unify editing approaches in Drupal for the whole stack and other related proposals.
Before patch (note overlay used as a general admin browser, elements like tabs, shortcuts, breadrcumbs, dark background):
After patch (same page never displayed in an overlay, because its not a contextual action):
After patch (sample screen of a form for which this new overlay is designed; no tabs, no breadcrumbs, close button and title inside, lighter background, drop shadow):