[Design] Design + Usability, Useful + Usable

[Matthew Eernisse]

Hank,

The single big functional difference between iCal and the Chandler 
collection selector is a requirement that we added to make it easier for 
people who aren't overlaying multiple collections: You shouldn't have to 
click twice to navigate between collections.

hank williams wrote:
> I dont see it. As far as I can tell chandler and iCal  have exactly
> the same underlying design in this regard. Chandler just makes it more
> confusing - almost seemingly with intent.
> 
> Also, iCal does another thing which I have said before I think would
> be helpful, which is the ability to hide the information panel on the
> right to minimize clutter.
> 
> Indeed much could be learned from ical.

In iCal, selecting a calendar also checks the checkbox (as you would 
expect) -- but that means that selecting a different calendar requires 
you to un-check your previous selection to remove it from the overlay. I 
personally find this pretty annoying, although I can see the benefit in 
the simplicity of it.

In Chandler, selecting a collection *overrides* the overlay state so 
that the collection is visible (whether it's checked or not). Naturally 
in a calendar view (and unlike Photoshop) there is no compelling case 
where you'd want to select a "layer," but not be looking at it.

This makes the UI significantly easier to use when you aren't using 
overlays, but it does complicate things. The overlay now has three 
states: visible, not-visible, and visible-only-by-virtue-of-being-selected.

Despite the visual confusion this creates (collections may be visible 
despite being unchecked), I'm also far from convinced that this is 
special enough to warrant inventing a completely new widget set.

For the selection-override, you could simply check-and-disable the 
checkbox to indicate that it's showing and can't be un-shown, and then 
return it to its previous state when selection goes elsewhere. This is 
what the first prototype I linked to in my previous e-mail does:

http://www.fleegix.org/demo/floss_usability_2007/proto_1.html

There are two drawbacks to this design:

1. The disabled checkbox tells you nothing about what the state was 
before the user selected the collection (and hence, what it will go back 
to if the user selects something else).
2. The user can't change it (from 
visible-only-by-virtue-of-being-selected to visible). To change it, the 
user would have to select a different collection.

The visible-only-by-virtue-of-being-selected state is what the colored 
eyeball in the second prototype attempts to convey to the user:

http://www.fleegix.org/demo/floss_usability_2007/proto_2.html

"In the overlay, but only there because it's selected." This design does 
not have either of the disadvantages of the previous design, but it does 
use a somewhat special UI element (the eyeball). That of course is 
mitigated by the following:

1. The eyeball is familiar to anyone who's used a graphics program.
2. The eyeball behaves precisely as a checkbox (all it's doing is 
replacing the check image with an eyeball, it still just toggles), so 
behavior is obvious.
3. The eyeball has obvious connotations of "visibility."

ICal decided to forego some ease-of-use in favor of simplicity.

We might be shooting ourselves in the foot by trying to make things even 
easier to use. Our requirement for single-click navigation complicates 
things -- but I still think we can preserve our existing functionality 
and simplify the UI for it.


Matthew