Re: [Usability] GtkEntry with units

[Matthew Paul Thomas <mpt myrealbox com>]

On Jan 17, 2007, at 4:19 AM, Robert Staudinger wrote:
> ...
> over at the abiword assembly line we're using a lot of GtkEntry
> widgets for displaying the size of stuff like page width/height, table
> cell size ... There is no recommendation how to handle a size with 
> units in the HIG. Well there is [1], somewhat related but not quite.
>
> So:
> + How to display a size with unit in a GtkEntry? Just append the unit
> part? Put the unit part outside the GtkEntry like [1]?

I think the answer to this is "it depends". If you can expect people to 
know what sort of units are available (probably true for page sizes, 
maybe not for cell sizes if they can be percentages), and how to type 
them (probably not true for angle measurements, for example), then you 
can make the units part of the entered text inside the field. 
Otherwise, you can provide an option menu of possible units next to the 
number field, like the Gimp does in its various dialogs for sizing 
images.

> + How to edit a size with unit? This obviously depends on the previous
> question. Should used units be changeable per GtkEntry? per App?
> global Desktop setting like LC_NUMERIC?

I think it would be reasonable to allow multiple units -- e.g. for a 
cell, height in ems and width in centimetres. If using a single field 
and a number is entered with no units, assume it's the same units as 
used for other dimensions of the same thing (if there are any), 
otherwise a global desktop setting if available. Fill in the guessed 
units when focus leaves the field.

> Should the unit be entered in "plain text" or using a dropdown? How is 
> the current unit displayed while editing is in progress? Can it be 
> overwritten?
> ...

If you take the route of using an option menu of possible units, one 
thing you might try is automatically switching focus from the field to 
the menu if a non-numeric character is entered, and from the menu to 
the field if a numeric character is entered. That way, no matter which 
of the two controls is focused initially, someone can type something 
like "8.25 inches" and it will do the right thing.

Cheers
--
Matthew Paul Thomas
http://mpt.net.nz/