Oleg,

well spotted - all auto-scroll implementations indeed do suck.

While I can't recall any such example of the top of my head, a good
alternative would be along the OS X Dock (enlarging focused icons) or some
kind of loupe UI - ie. keep the whole context in one page in a scaled down
version, and zoom a selected partial area to full-resolution to allow the
drop. This removes the "variable speed" and "opposite end of window to
reverse direction" problems you outlined.

Jakub

On Mon, Dec 1, 2008 at 12:05 PM, Oleg Krupnov <[EMAIL PROTECTED]>wrote:

> It's been a classic design principle that any scrollable view should
> auto-scroll when an object is dragged outside or close to boundary of
> the view.
>
> Here's what Alan Cooper wrote in his "About Face" book:
>
> "Auto-scroll is a very important adjunct to drag-and-drop. Wherever
> the drop target can possibly be scrolled offscreen, the program needs
> to auto-scroll. Any scrollable drag-and-drop target must auto-scroll."
>
> However I've suddenly realized that I've never seen any implementation
> of auto-scrolling (including my own :) that would not SUCK.
> Auto-scrolling is perhaps the most awkward feature associated with
> drag-and-drop that I would name.
>
> IMHO, auto-scrolling sucks because:
>
> 1. It lacks control over precision. Variable auto-scroll rate sucks
> because when I want to scroll faster (and I always do :), I often
> over-scroll. Then I need to drag the object to the opposite side of
> the screen and auto-scroll back.
>
> 2. It is not informative nor it is flexible. At the beginning, you
> don't see how far you may need to scroll, so I usually pick the
> fastest rate and over-scroll, as in 1. or have to wait too long if I
> take a low scroll rate. The transition from lower to faster scroll
> rates appears abruptly and often cause over-scrolling.
>
> 3. It is slow. First, you have to wait until it starts in vicinity of
> the view border, then wait until it scrolls with a particular speed.
>
> This all ends up in that with auto-scrolling I never feel comfortable
> and confident, but often strained and lacking control.
>
> This made me think about good alternatives to auto-scrolling. What do you
> think?
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