Preface

When I started thinking about this topic about a week ago, it was originally going to be a rant about NetNewsWire and how its click-through behavior was so frustrating. Upon doing a little research however, I discovered this problem is not specific to NNW, but all OS X applications, and I’m certainly not the first person to talk about it (John Gruber has a number of interesting reads). I have stumbled upon something however that I’ve been unable to find mentioned elsewhere online, and that’s the inconsistency between single and double click-throughs in an application.

First, a definition from the Apple Human Interface Guidelines to make sure we’re all on the same page, and not talking about banner ads –

An item that provides click-through is one that a user can activate on an inactive window with one click, instead of clicking first to make the window active and then clicking the item.

Often, click-through is discussed in terms of whether or not an inactive application “receives” the click. Developers have the choice of making click-through active on most any object within an application, and there are various schools of thought on what should and should not allow click-throughs. I’m more interested however in “double click-throughs”, or whether an application receives a “double click” message when it is inactive.

An illustration

As I’ve already mentioned, this all begin with an annoyance I discovered in NetNewsWire; here’s my basic workflow

• browse through headlines in NNW
• open full article text in Safari
• after reading article, close Safari window and click back to NNW

This works okay, unless in clicking back to NNW I want to select something other than what is currently selected. For example, if I currently have CNN.com as my selected feed, and I click on my Slashdot feed with NNW being inactive, then all that happens is that NNW becomes the active window. I must then click once again to actually select the Slashdot feed – this is completely expected behavior when click-throughs are turned off. What is not expected however, is that if I perform this second click too quickly, then NNW receives a double-click action and opens the Slashdot homepage in my browser. The problem is that NNW does not allow single click-throughs but it does allow double click-throughs. The only way to make a new selection in NNW while it is inactive is to click once to make it active, pause for a moment, and then make your actual selection. Talk about annoying!

I realize I’m kind of picking on NetNewsWire, but that’s only because this is where I first noticed the issue. Apple applications are no exception - this inconsistency in click-throughs can also be found in iChat’s Buddy List window and Mail message listings (though I’m sure there are many others). iTunes’ track window seems to behave consistently however – neither single or double click-throughs are registered – so apparently it is possible.

The Remedy

I’m certainly not a skilled interface designer, so I’m not about to jump into the debate (religious war?) of when click-throughs should and should not be allowed. I am however quite skilled at the role of “end-user” and can recognize inconsistency when I see it. I’ve only toyed in Interface Builder quite briefly, so I don’t know if it has different properties for single and double click throughs. If not, I would suggest some mechanism for consistency be added, and if it’s already there then I would suggest to developers to use the same value for both.