[install-discuss] Re: Re: Dwarf GUI Demo available

[Frank Ludolph]

The general GUI principle "don't off something that isn't available" 
shouldn't be used if it creates "can you figure out why this isn't 
available?" I was part of the team that created the first principle and 
I have watched people struggle with its result "can you figure out 
why...", as have I, during the intervening 25+ years. ;-)

There is always a trade-off between explicit information, effective use 
of the available screen space, and visual clutter. The latter two raise 
considerable usability issues of its own when we try to force too much 
into too little space. We need to design for the primary task. Remember 
that the user very likely already has a specific disk in mind for the 
install and will look for and select that disk directly, ignoring the 
others, so we want to make locating a specific disk as easy as possible 
even if it isn't usable. If we knew in advance which disk he is looking 
for we wouldn't even show the others. :-)

The emblem tells the user that the disk isn't usable. The high-order bit 
of information is immediately visible. The message, definitely the 
second-order bit, is visible only when selected thus reducing visual 
clutter and saving screen space that can be used for more high-order 
information. We don't show the message on roll-over as that action 
already provides additional information about the disk, e.g. disk 
manufacturer and perhaps controller info, to enable the user might use 
to more accurately identify the actual disk. Combining both 
identification and error information creates a confusing situation and 
forces the user to mentally separate the two messages.

The warning triangle will be used in cases where the disk is usable but 
there might be some sort of issue of limitation in its use. Not sure 
what these might be yet, but expect that they will arise.

Frank


Michael Pogue wrote:
> Yes -- I like that idea as well. It addresses the general GUI 
> principle "don't offer something that isn't available" (also known as 
> "Want this? Can't have it.") :-)
>
> If the circle with a line through it is still not enough info, we 
> could alternately overlay a yellow warning triangle and some text "too 
> small for installation", or "not enough space", etc...that would both 
> make it not selectable, and make it clear why it wasn't available for 
> selection (before it was clicked on).
>
> Mike
>
> Shawn Walker wrote:
>> On 06/04/07, William D. Hathaway <william.hathaway at versatile.com> wrote:
>>> If disks that are too small (or otherwise invalid choices) can't be 
>>> "unselectable" can the icons for them be different at least (like a 
>>> hard disk image behind a "circle with a line through it") than the 
>>> legal disks?  If I have 10 disks, but 9 are too small to install on, 
>>> it seems tedious to make the user select all 10 one by one before 
>>> finding the disk that it is legal to install on.
>>>
>>
>> The different icon seems like a great compromise, that way people can
>> still select the disk in question to find out specifically why it
>> can't be used.
>>
>>> I'm not sure what ordering the disks are displayed in, but I'd also 
>>> recommend making the first usable disk be in the position that users 
>>> would be most likely select (the disk on the far left or top 
>>> depending on how the layout goes).
>>>
>>
>> That also seems helpful.
>>
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