From KDE UserBase Wiki

    User Assistance

    User Assistance guidance considers interface elements that inform users of the application’s activity and status, as well as elements dedicated to user education. This includes online help, error alerts, and status alerts.

    User-driven information

    • Tooltips - Use tooltips for user driven information.
    • Callouts - Use callouts for user driven information coming from desktop widgets.

    System triggered notification

    • Message panel - Use a message panel to inform users about non-critical problems.
    • Notification - Use a notification as system-triggered message to inform about events that are outside of the current context.
    • Progress indicator - Show a progress indicator for lengthy actions.

    Disruptive messages

    • Message dialog - Show a modal message dialog if the processing has reached an unexpected condition that requires immediate interaction.

    Help system

    • Help - Provide a help system as a secondary mechanism to support users’ complete or better understanding of tasks — the primary mechanism should be the user interface itself.