Apple Mouse: USB Overdrive does not work for background windows

Posted by Pierre Igot in: Macintosh
November 23rd, 2009 • 4:22 pm

Last week, I wrote about using USB Overdrive to customize the behaviour of the Apple Mouse in the Preview application in Mac OS X.

Unfortunately, there was one thing that I failed to note at the time and that makes USB Overdrive a less than ideal solution.

That thing is that there is a particular feature of Mac OS X that USB Overdrive simply does not support, and that is the ability to scroll through a background window whose parent application is different from the current application.

In Mac OS X, if you hover over the visible portion of a scrollable background window with your mouse pointer, when you use the Apple Mouse’s scroll ball, it will cause the background window to scroll without requiring you to bring the background window to the background. (Of course, this only works for background windows whose parent application is a properly behaved Mac OS X application, so that excludes Microsoft Word.)

I find this “scroll-through” very handy, but it poses a serious problem for a third-party tool such as USB Overdrive. Because USB Overdrive controls the behaviour of the mouse based on its settings for the application that is currently in the foreground.

This means that, if you use USB Overdrive to enforce a customized behaviour in Preview, in accordance to what I described in my post last week, the customized behaviour will only work when Preview is the foreground application. If Preview is a background application and you scroll the Apple Mouse’s scroll ball while hovering over a background document window in Preview, the scroll ball’s behaviour will be the behaviour defined in USB Overdrive for the application that is currently in the foreground.

And conversely, if Preview is the foreground application and you hover a background document window whose parent application is a different application, when you try to scroll through the background document using the scroll ball without bringing the background document window (and its parent application) to the foreground, USB Overdrive uses the scroll ball setting for Preview and not for the document’s parent application.

Unfortunately, I am so used to being able to scroll through background windows that I simply cannot get used to the limitations imposed by my customization of the scroll ball’s behaviour in Preview with USB Overdrive. So I have had to turn it off and switch back to standard settings for Preview, which means that I’ll have to live with the scroll ball’s excessive sensitivity in single page view mode for PDF documents in Preview.

I don’t know if there is anything that the developer of USB Overdrive can do about this. The entire design of his utility is obviously application-centric, like most things in Mac OS X. The “scroll-through” behaviour that Mac OS X offers in well-behaved applications is a behaviour that transcends application boundaries and, as such, is not compatible with an application-centric approach.

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