[Interest] OS X: making an application an "agent"

[René J.V. Bertin]

Hi,

There are 2 ways in which an OS X application can be turned into an agent, i.e. an application that has no presence in the Dock and doesn't show up in the App Switcher:

1. Set LSUIElement to true in the app bundle's Info.plist
2. Do the same thing programmatically :

    CFBundleRef mainBundle = CFBundleGetMainBundle();
    if (mainBundle) {
        // get the application's Info Dictionary. For app bundles this would live in the bundle's Info.plist,
        // for regular executables it is obtained in another way.
        CFMutableDictionaryRef infoDict = (CFMutableDictionaryRef) CFBundleGetInfoDictionary(mainBundle);
        if (infoDict) {
            // Add or set the "LSUIElement" key with/to value "1". This can simply be a CFString.
            CFDictionarySetValue(infoDict, CFSTR("LSUIElement"), CFSTR("1"));
            // That's it. We're now considered as an "agent" by the window server, and thus will have
            // neither menubar nor presence in the Dock or App Switcher.
        }
    }

Typical "agent" applications are those that only provide an icon and menu in the "systray" (icons on the RHS of the global menubar), but any background application that needs to be able to post dialogs or even receive GUI events (think read keystrokes) will need to be such an agent.

The QPA cocoa platform does have a function which does more or less the opposite (qt_mac_transformProccessToForegroundApplication, sic!) but I don't see to create an agent. Is there? If not, would it make sense in e.g. the MacExtras component?

R.