install_inspector draws gpui's debug inspector in Ely's look: a panel
with the picked box's source, ids and box model, and its margin,
border, padding and size drawn over the page through raise, since the
panel scrolls. FpsMeter counts frames on the executor's clock and
colors each by the frames it missed. RenderCounter counts the renders
of the view that draws it. EventLogger lists the input that reaches
what it holds, its canvas laid first so a child's stop hides nothing.
tooling::Playground lays a preview beside its knobs, each a switch, a
choice or a number that edits one property; the preview redraws from
the settings, which fail on a name or kind the knobs lack. The gallery
app is the ComponentGallery; its page 43 shows both.
ZacharyZhang-NY