Widget index / Windows and dialogs · Download this HTML
Ready — try the example.
States and behavior
Question, destructive action, safe initial focus/default and explicit outcome.
Keyboard
Enter initially cancels; Tab reaches Delete; Escape cancels; focus returns to the trigger.
Scope and adaptation
Action labels say what will happen. A destructive choice should not become the initial default merely because it is visually primary. Nothing on disk is removed.
Sources
Microsoft preliminary guide (1995), chapters 7–8 · Modern browser accessibility pattern
Original implementation; system colors are represented by CSS variables. The default 13 px system-font stack is a readable browser adaptation. The 1995 source is preliminary, not a final product specification. Test the target browser and native host before shipping.