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List:       kde-core-devel
Subject:    Re: [Fwd: Usability and open source]
From:       Richard Moore <rich () ipso-facto ! freeserve ! co ! uk>
Date:       2000-01-31 14:06:26
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Stephan Kulow wrote:
> 
> --
> It said Windows 95 or better, so in theory Linux should run it
>                                                 GeorgeH on /.
> 
>   ------------------------------------------------------------------------------
> 
> Subject: RE: [Fwd: Usability and open source]
> Date: Mon, 31 Jan 2000 13:53:28 +0100
> From: "Ben Last" <ben@last.uk.com>
> To: <kde-look@kde.org>, <kde-core-devel@kde.org>
> 
> > From: Richard Moore [mailto:rich@ipso-facto.freeserve.co.uk]
> > I understand Fitt's law, this technique increases the clickable area of the
> > widget and so should increase the Fitt's value.
> Sorry, Richard, but I still disagree!  The Fitts value ("depth") is a function
> of the clickable area and the position (ie something in the corner of the
> screen is infinitely deep because the mouse pointer can be thrown into the
> corner and will stick there).  In the case we're discussing, you're not

I know, though I think this is slightly simplistic given the formulation of
the law I was taught (area / d^2), in this case the net result of the supposed
infinite width is zero. I know this is not true in practice, but it emphasises
the need for real world testing to make a sensible evaluation.

> increasing the clickable area at all, you're making it more likely that the
> mouse will stick there.  I contend that since one can't predict what

True, but the question then becomes how do you measure the distance? Given
that the mapping between mouse movement and pointer movement is not fixed
(because of mouse acceleration) I would contend that the size of the screen 
representation is not an accurate measurement. I am perfectly willing to
concede this argument for now, because as soon as I finish the code we can
measure how well it works in practice. If it doesn't work then we can move
on, if it does then we can decide how (and if) we want to use it.

> button/icon/doobrie the user wants to click on, you'll end up frustrating her.
> Like trying to select one magnet from amongst a bunch of them with a metal bar.

I have tried to ensure that this does not happen, we'll see whether I got
it right in a few days.

> 
> > This is a non-issue as most widgets where the class would be useful have
> > tooltips which means mouse tracking is enabled anyway.
> Okay, you got me there :-)  Though I could argue the utility of tooltips!

 :-)

Rich.

> 
> cheers
> ben

-- 
     Richard Moore		rich@ipso-facto.freeserve.co.uk
http://www.robocast.com/	richard@robocast.com
http://developer.kde.org/	rich@kde.org

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