Alert dialog

ui.AlertDialog asks about something important over the window while a *bool is true, as AppKit's alerts: a title, a message, and buttons, the last of which is the default, in the accent color, with the focus, which Enter clicks. Escape closes the alert choosing no button, as canceling does, whatever the buttons say, in any language; a click outside the alert does nothing. It returns the index of the button clicked, in the frame it is, which closes the alert, ui.AlertDismissed in the frame Escape closes it, and -1 otherwise.

if ui.Button(c, "Delete").Clicked() {
	app.asking = true
}
switch ui.AlertDialog(c, &app.asking, "Delete “Notes”?", "You can't undo this.", "Cancel", "Delete") {
case 1:
	app.delete()
}

An alert that must be answered stays open by setting the *bool back to true as Escape dismisses it:

if ui.AlertDialog(c, &app.updating, "Update required", "Restart to finish updating.", "Restart") == ui.AlertDismissed {
	app.updating = true
}

The alert grows past its usual width as far as the window allows to keep its buttons on one line, with its title and message wrapping to that width. In a window too narrow for that the buttons wrap onto more lines, and a label too long for the alert ends in an ellipsis.

For a dialog of your own content, use a dialog; for a choice the user can undo, act at once and offer it in a toast.

Accessibility

Assistive technology sees an alert dialog named by its title and described by its message, with the focus on its default button.