Sebastian Rittau's Blog

Several applications need to know about user activity. This includes screen savers, RSI prevention tools like Workrave, and IM programs (for automatic away message). Currently each program has to implement activity tracking itself. This means that there is no unified configuration, but also that programs like movie players have to resort to hacks to prevent screen savers from activating. It's also not possible for users to trigger a generic "away" event that causes the screen to be locked, the IM program to set the away status etc. pp.

A unified system would have the following requirements:

• There needs to be an idle time, after which screensavers could active. for example.
• There needs to an away time, after which the user is considered to be AFK. This could trigger screen locking, and IM status changes.
• Programs must have the ability to signal user activity, so that screen savers won't activate while watching a movie.
• Programs must have the ability to temporarily shut the activity listening off. This is needed by xlock-like programs, where the program itself is the only authority to reenable user activity.

A central daemon (yay, another daemon!) communicates with other program via d-bus. This daemon listens for user activity, i.e. mouse movement and key presses. Basically there are four user states:

busy

The user is currently using the computer.

lazy

The user hasn't used the computer for a set amount of time.

away

The user is away from the keyboard.

locked

Like "away", only that wakeup events are ignored until the mode is manually changed.

In general the possible mode changes are busy → lazy, busy → away, busy → locked, lazy → busy, lazy → away, lazy → locked, away → busy, away → locked, and locked → busy.

The following messages are sent by the daemon:

idle

This specifies are reason for the status change as parameter, for example "timeout:600", meaning that there was no user activity for 600 seconds. This message may be repeated with reason "repeat".

away

This message is sent when the user is away. It also includes the reason, for example "timeout:1200" or "userrequest". It may also be repeated.

busy

This message is sent when the user returns to work. It has an optional reason parameter, and may be repeated.

The daemon understands the following messages:

activity-ping

This is sent by some applications, like movie viewers every few seconds to signal that the user is busy, although there is no user activity.

gone-away

This is sent by applications when the user explicitly toggles the away status, for example by selecting "lock screen" from the system menu.

locked

Similar to gone-away, only that auto-wakeup is disabled. The only entity to reenable listing to events is the sender of the locked message. Therefore a detail string must be passed. This is used by xlock-like applications to prevent applications from changing the "away" status, just because someone moved the mouse.

unlocked

The corresponding unlock signal to the locked message. Must use the same detail string.

Screen Saver

When the screen saver receives the away signal, it turns on the screen saving (if it's not already running). If it receives the busy signal, it turns of the screen saver. It ignores the other signals.

Away Button

When a user uses a potential away button in the system menu, the menu sends the "gone-away" message to the daemon.

Screen Lock

When a user uses the "Lock Screen" button in the system menu, the menu sends the "locked" signal to the daemon. It starts the screen saver and listens to user input. When the correct password has been entered, it sends the "unlocked" signal and ends the screen saver mode.

Screen Saver with Locking

When the screen saver receives the away signal, it starts screen saving, and sends the "locked" signal to the daemon. When there is user input and the correct password is entered, it sends the "unlocked" signal.

Instant Messengers

When the IM program receives the "away" signal, it turns on the auto-responser and possibly the away method. The auto-responder message may be modified according to the reason detail parameter. When the IM program receives the busy signal, it turns auto-responding and away status off.

• The current proposal does not address RSI prevention programs like Workrave.
• Security implications of the locked mode.
• The disparity in screen saver responsibilities between normal screen saver activation and xlock activation.