Dock — NameThatUI

Click an app to open or quit it: the small dot under its icon is the open-app indicator
/ NSDockTile · NSApplication.dockTile /
also called Mac Dock, app dock, application dock, taskbar (Windows term)
“The little black dot under an app icon” is the open-app indicator on the Dock, the Mac's floating bar of app icons at the bottom of the screen. The apps you keep sit first; after a thin divider come open apps you didn't keep plus up to three suggested and recent ones, and after a second divider the folders (stacks) and the Trash. The system draws all of it: an app controls only its own tile (NSDockTile), its right-click Dock menu, and whether it has a Dock icon at all. The dot is not the red count on an icon's corner (that is a Dock badge), the Dock is not the menu bar along the top, and Windows calls its version the taskbar.
“The little black dot under an app icon” is the open-app indicator: the system puts one under every app that is running, and the setting that hides it is called Show indicators for open applications.
“The extra line between my apps” is a divider, which Apple calls a separator line: one stands before the suggested and recent apps and one before the folders and the Trash, so the first one is gone when the recent apps section is empty.
“The apps I didn't add, between the two lines” are the suggested and recent apps: apps that are open but aren't kept in the Dock, plus up to three used lately, turned on and off by the setting Show suggested and recent apps in Dock.
“The folder shortcut next to the Trash” is a stack: a folder kept in the Dock, Downloads by default, that opens as a fan, a grid or a list when clicked.
Work with the macOS Dock. The system draws the shelf, the open-app indicator (the small dot under each running app), the divider lines and the stacks, so an app controls only its own tile (NSApp.dockTile), its Dock menu (applicationDockMenu(_:)) and whether it has a Dock icon at all (NSApplication.ActivationPolicy.accessory for none). To mock one, build a floating, rounded, translucent shelf that hugs its icons, with a small neutral dot under open apps and one thin line before the recent apps and one before the folders and Trash; never a full-width taskbar.
Paste this, then describe what you’re seeing — it hands your agent the classic failure modes to rule out first.
Debug my app's presence in the macOS Dock (NSDockTile, applicationDockMenu(_:), NSApplication.ActivationPolicy). Rule out: expecting to draw, recolor or hide the open-app indicator, which only the system and the user's Desktop & Dock settings control; an .accessory or LSUIElement app that never gets a Dock icon or a dot; the dot staying after the last window closes because the app is still running; a Dock menu built once and never refreshed; custom NSDockTile.contentView drawing that never shows because display() was not called; looking for a divider API when the lines belong to the system. The symptom:
The exact names this thing goes by in code — each row is one framework’s word for it. Use the row that matches your project (or paste it into your prompt).
the visual dictionary of ui
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