User Centered

The topic du jour is context sensitive scrolling you can do in differing text areas in web pages. "The what now?" you ask? Okay- you have the overall page scrollbar that you can control with a mouse wheel (this post is talking about just scrolling- no clicking to 'pan'). In addition, say you're on a page with a form and you've got a text area with its own scroll bar. If you didn't start browsing yesterday, you've noticed that if you hover your mouse over this textarea, you can control that textarea scroll bar by rolling the mouse wheel. Its a context, or mode; the scroll wheel changes what it manipulates based on the where it's at on the page. See the portion of gmail at right. Two scroll bars, and depending on what you're pointing at, you scroll different things.

I know modes and context are taboo in usability, but I actually find them quite useful in browsing/using the mouse. With only a guess to back me up, I'd say it's easier to have contexts with a mouse since since you're generally paying attention to where the mouse is currently pointing (if you're scrolling the wheel, it's actually in your hand and you're controlling it). That is a user controlled mode switch. You're moving the mouse over the text area, so it's more likely that you know what context the mouse is in (granted, that may not be clear the first time around, but you learn it quickly).

The problem arises when the system pops you out of that context when you don't explicitly tell it to do so. That's when things get slightly confusing, or in the case of scroll bars, annoying.

You'll notice in most browsers, if you have your mouse over a text area and you reach the end of your scrolling, control is automatically switched back to the page scroll bar. So... if you were trying to just scroll to the top of your text area to insert something at the top, when you get there, you're all the sudden scrolling way above the text area.

What are your thoughts on this? Is it annoying or useful for you? Do you like having the control switch like that? I've found it most annoying when I'm trying to scroll an entire page and my cursor scrolls over a textarea...it's like dropping into some quicksand for a second. I have to move out and get back on task.

Ideally, if I initiate my scroll (ie- get my scroll on) at the page level it should keep the control at that level. At LEAST until I complete the first scroll (ie- take my finger off the wheel and move it back to the origin to scroll again). And if I start out in a form element, I'd like the browser to force me to move my cursor away from it, back to the page, so that I can control the page scrollbar. These are not fool-proof, but they give the user more control over the "mode switch."