Tab key does nothing when a dialog box pops up — you can't keyboard-navigate buttons
A dialog appears with Cancel and Don't Save and Save buttons. You try to Tab between them to select without using the mouse. Nope. Tab does nothing. You're forced to reach for the mouse every single time a dialog appears.
Why does this happen?
macOS restricts keyboard navigation to text fields and lists by default. Full keyboard control including navigating buttons in dialogs with Tab has to be explicitly enabled. It's off by default, which is baffling from an accessibility standpoint.
How to fix it
System Settings → Keyboard → turn on Keyboard navigation (macOS Ventura+) or check Use keyboard navigation to move focus between controls (older macOS).
Now Tab cycles through all UI elements including dialog buttons. Press Space to activate the focused button.
Bonus: in most dialogs, pressing Return triggers the default button (highlighted in blue) and Escape triggers Cancel — no Tab needed for common cases.
Discussion
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