In Comparison: Multiple Selection, part 1
How often do you think about the details of the basic interactions that make up the OS you use on a daily basis? Last week, I had to specify the behavior for multiple selection of list items in a browser-based application. The customer’s requirement asked for shift-clicking and control-clicking, just as you would find on the desktop. With the intent of making the behavior exactly like desktop OS behavior, I analyzed both Windows XP (which will be installed on the machines our application will be used on) and Mac OS X Lion. Unsurprisingly, there are significant differences between them. I’ll start by describing shift-clicking now, and continuing with control-clicking tomorrow.
As you likely know, shift-clicking selects contiguous items in a list. So, if you click item 1 to select it, and then shift-click item 5, items 2, 3, and 4, will be selected as well. That’s clear enough, but let’s dig a little deeper. Feel free to follow along.
What happens if you have a series of contiguous, selected items, and then shift-click to add to the selection? For example, you have selected items 1 through 3 by clicking 1 and then shift-clicking 3. Now, let’s shift-click item 5. Sure enough, item 4 is selected too, and we end up with items 1 through 5 selected. Now try this: click item 3, then shift-click item 5. Items 3, 4, and 5 are selected. Now shift-click item 1. What happened? Items 4 and 5 deselected, and items 1 and 2 selected. Item 3 remained selected, so we now have items 1 through 3.
As it turns out, the OS is setting anchors on clicks, but not on shift-clicks. In other words, it remembers that you clicked on item 3, but forgets about the shift-click on 5. I consider this behavior to be counterintuitive; I would expect items 1 and 2 to be added to the selection without losing 4 and 5. This behavior is identical in Mac OS X and Windows XP.
