I updated Screen Dimmer for Mac OS X 10.6. It’s a recommended update for all users of Mac OS X 10.5.x too.

As you should have already noticed, both System Preferences and screen saver engine are now 64-bit applications, which means they cannot load 32-bit plug-ins. Since all screen savers are, in fact, plug-ins, this means they don’t work any more on Snow Leopard.

Besides recompiling Screen Dimmer as a fat binary (where “fat” is “really fat”: 32-bit PowerPC, i386 and x86_64) I had to make a lot of changes because Snow Leopard turned out to be a very different beast under the hood. First of all, the new System Preferences application seems to use garbage collection which for reasons I cannot explain failed with Screen Dimmer loaded. Its memory usage exploded in a matter of seconds, reaching a gigabyte before I could kill it. I made sure I don’t leak any memory but it still happened. I had to refactor my code to eliminate this behaviour.

Then I noticed that the option to ask for the password no longer works because it just doesn’t get saved. The preferences system of Mac OS X spins some weird gears I refuse to understand. For example, we have that ByHost folder inside the Preferences folder and it drives me nuts. The screen saver preferences are usually kept there. But Snow Leopard somehow insists that if your screen saver has a default key named “askForPassword”, it should be saved in the Preferences folder instead. Worse yet, it ignores this default when you request it in your code, presumably because it reads your preferences from the ByHost folder. So I had to rename the key and, as a result, your ask-for-password setting is lost in migration to 10.6. Sorry about that.

I also fixed an old bug where sometimes the fade-in duration is not remembered properly.

Now it looks like the updated version will work until 10.7. If you are still running Mac OS X 10.4 and cannot upgrade, the old Tiger-compatible version is still available too.

Posted on Sunday, September 6th, 2009 at 14:05 under Announcements, Coding, Mac OS X.
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