[REVIEW REQUEST] Add text property to ComboBox

[Jonathan Giles]

>>> But that aside, you really are assuming having the editor to be a text
>>> component of some sort. For entering color I may, for example have a
>>> container with three text fields (RGB). Can I not do so?
>>
>> I put forward that text will very often be a common input method, so
>> support for it should be added at a low level. But you do have a good
>> point; multiple text fields...
>
>
> Or sliders (RGB for a color, again). Or ... anything.
>
> Why not?
>
> Since ComboBox has a type parameter, I would expect to be able to 
> provide whatever editor suits better to the encapsulated type.
>
> As a consequence, an edited value - a value in the editor - may not be 
> representable by String. Hence, again, <code>T editedValue;</code>.
>
> That was my point, yes.

This is the same as my previous email - the ComboBox<T> type parameter 
does not necessarily reflect the input method, just the data type of the 
value property. Input can be String based, and converted to T via a 
StringConverter.

For custom editors, this again should not be done via ComboBox, but 
rather ComboBoxBase. As I've mentioned previously, ComboBox is a 
specialisation of the ComboBoxBase class to provide the most commonly 
used functionality, that is a TextField for input, and a ListView for 
showing the available options.

-- Jonathan