[GUI] Mission Statement

[Axel Simon]

On Thu, Mar 06, 2003 at 12:23:03PM +0100, Daan Leijen wrote:
> Hi Axel

> There are a few errors regarding the back-ends:
> 
> * Qt supports win32, bare X11, and MacOSX. However, none of these
> platforms is supported with native look-and-feel but via Qt themes.

I think I need to make it clearer what the table is meant for.

IMHO, we propose some functionality for the CGA, then go and (try to)  
implement it, revise and then mark the functionality as stable. Everything
we specify in the CGA has to conform to the native look-and-feel of the
particular platform. For every cross in the table, there is someone who
takes care that there is
a) a binding for the CGA functionality proposed and
b) that this functionality complies with the native look-and-feel.
In particular, a cross does not mean "it will run" but a cross means that 
there is somebody out there who takes care that the functionality in the 
CGA is implemented via this backend on this platform with the native 
look-and-feel. The means, if we put a cross down for wxWindows and Mac OS, 
you (or someone working on the wxWindows backend) has to make sure that 
the GUI components we propose has the native look-and-feel on the Mac OS 
platform.

Ideally, a program written with the Common GUI spec, compiled with 
wxWindows or the native Aqua interface should be indistinguishable.

> However, they are very good at achieving almost native look-and-feel and
> it takes an experienced user on windows to see the difference. On KDE,
> Qt is considered the native look-and-feel.
 ...and as far as I understand Qt is defining the look for KDE as Gtk is 
defining the look of Gnome. The feel is probably highly underspecified 
under Unix (which means we are more flexible there).
> 
> * You forgot to add Tk, supports all platforms, albeit slowly and not
> always natively.
 Is there anybody willing to do a binding? Even if so, there is no 
platform where Tk delivers local look-and-feel, is there?

> * Same for Java AWT via JAPI.
 Same thing here. It might of course be possible to write backends that 
exhibit the Common GUI API, but they will not achieve native look-and-feel 
which means we don't have to worry about those while we are trying to 
specify CGA.

[..]
> * You write: "If discrepancies in look-and-feel is not a big issue, they
>  would choose a back-end like wxWindows to run on all platforms"
> This is not true at all -- people tend to choose wxWindows over Qt *because*
> it offers native look-and-feel. Use Qt or Tk as your example.
 According to Wolfgang, there are things which do not look native and
-more important- do not feel native. Most people said this is true for
full fledged GUI libraries. That's why we don't try to build one but go
for a subset ("Look-and-feel" in Section 2).

> * "This backend [wxWindows] might not give access to all functions available
>  on a platform"
> In contrast, wxWindows normally gives *more* functionality than is natively
> available by implementing that functionality on top the native interface.
> Examples are advanced tree and list controls, or MDI frames. Use, uhh, X11 
> as your example here :-)
 Providing widgets beyond those of the native platform is a violation of 
look-and-feel by definition.

As soon as the document is in GHC's CVS, editing will become easier and 
I'd like people to join in. For now, I just have to ask what to change and 
I am grateful for any input.

I changed the table and the last two sentences of "3.2 Back-ends". Updated
version at http://www.cs.ukc.ac.uk/people/staff/as49/poll.pdf

Thanks,
Axel.