Desktop pinning
The core trick of Umbra is a window that behaves like part of the desktop. It lives in DesktopPin.cs and Native.cs.
Owned by Progman
Section titled “Owned by Progman”Each widget window is owned by Progman, the desktop shell window. An owned window is shown and hidden with its owner and stays above it, which keeps widgets visible when you press Win+D (which minimizes ordinary windows but leaves the desktop). The ownership is re-applied when the window is shown and when Explorer restarts, so a crashed shell doesn’t strand your widgets.
Kept at the bottom
Section titled “Kept at the bottom”The window is a tool window (not in the taskbar or Alt-Tab) and every WM_WINDOWPOSCHANGING message is rewritten to HWND_BOTTOM, so apps always cover it, whatever they or Windows try to do to the z-order. Peek temporarily lifts them, then puts them back.
Never activates
Section titled “Never activates”Widget windows have no activation: clicking one doesn’t change which app is foreground. They get keyboard focus only right after a physical mouse press on them (WidgetWindow.TakeKeyboardFocus), so a widget can’t pull focus while you type elsewhere. The page’s umbra.requestFocus() is honoured only in that situation.
Why it’s sharp
Section titled “Why it’s sharp”Rainmeter-style skins draw on translucent layered windows, where Windows disables ClearType. Umbra’s windows are opaque true black, with DWM-rounded corners and a hairline border drawn by DWM, so text renders with full DirectWrite quality. On OLED, black pixels are off, so the card seems to float on the wallpaper.
The edit-mode pill
Section titled “The edit-mode pill”EditPill.cs draws the “Editing widgets · Snap · Done” pill as its own non-activating, Progman-owned window just above the widgets. It’s not a WebView, so it never appears in a capture.
Edit mode overlay
Section titled “Edit mode overlay”In edit mode, unlocked widgets are covered by Umbra’s overlay with an outline and a corner handle. The host moves, resizes and zooms only during a physical mouse press (move, resize) or while Ctrl is physically held (zoom), never because a page asked. See the security model.