[kde-guidelines] Drop-down list and Combo box

[Thomas Pfeiffer]

On Friday 07 June 2013 17:28:26 Heiko Tietze wrote:
> IMHO we should distinguish between simple, read-only drop downs and combo
> boxes. But some of the underlying ideas, and probably the code as well, are
> very similar. So I put both into the old ComboBox article.
> 
> http://techbase.kde.org/Projects/Usability/HIG/Combo_Box

Agreed! The problem is that common naming and Qt naming collide here. In Qt, 
afaics, both a drop-down / select box and an actual combo box are a ComboBox, 
one with "editable" set to "false", the other with it set to "true". And then 
there is a KComboBox, which is an extended ComboBox that among other things 
has an "autocomplete" option.

If now we refer to the same widget with an option set to one value or another 
with different names (one being the same that Qt uses) could lead to confusion 
among developers.
On the other hand, I don't know how the respective Plasma Components (or Qt 
Desktop Components, for that matter) are or will be called. Looks like 
confusion all over the place.
Developers, can you help us here?

And I've seen a hybrid of simple drop down and combobox (outside of KDE) as 
well: It provides autocomplete function without allowing new entries. It 
simply does not accept input that is not part of its existing list of options. 
Is that a third type?
 
> Open for discussion...

Generally, I really like the improvements!
For detailed feedback (and some questions for the developers among us), I'll 
copy some bullets to comment on here:

> Use a drop-down list for single selection of one out of many items.
> For a single selection out of a large number of items, use a list view.

What's the exact distinction here? Personally, I'd distinguish mainly based on 
available space. If there is enough vertical space for a tall list box, it 
works better for single selection because you can see more options at once. If 
you don't have the vertical space, you have to use a drop-down anyway.
Not sure if that is a sufficient criterion for distinction, though.

> Enable vertical scrollbar for drop-down lists with more than eight items.

Devs: Does this have to be enabled explicitly or does it appear automatically?

> Do not add controls to the drop-down (e.g. check boxes for each item).

Devs: Is this even possible technically?

> Provide autocomplete for the whole string and not for only the last letter, 
i.e. ABC must not go to the first entry starting with "C".

Devs: Does the autocomplete option of KComboBox provide that automatically?

Cheers,
Thomas