[Development] Behavior change: A sane and consistent QPainter coordinate system in Qt 5

[BRM]

----- Original Message -----

> From: Sorvig Morten <Morten.Sorvig at digia.com>
> Subject: Re: [Development] Behavior change: A sane and consistent QPainter coordinate system in Qt 5
> 
> 
> On Oct 11, 2012, at 1:57 PM, Samuel Rødal <samuel.rodal at digia.com>
> wrote:
>> 
>>  It's unfortunate to potentially cause some extra trouble for a subset 
> of 
>>  existing applications that wish to port to Qt 5, but weighed against the 
>>  utter embarrassment of the current fill rules I think we need this change.
> 
> 
> +1 from me for "utter embarrassment".
> 
> A slight tangent, perhaps we should be less afraid of making behavioural changes 
> to Qt in minor releases, as long as they are flagged and old behaviour can be 
> restored. The flags could serve for say 3 minor releases and then be retired 
> together with the old code path. An even softer path could be to make changes 
> opt-in, then opt-out, and finally mandatory over the course of several minor 
> releases.

How about opt-in (via configure or extra flags) until the next major release?
I don't think doing the opt-in/opt-out/mandatory over several minor release would bode well for compatibility between minor releases, which is a big must.

For example, I have some software that is still running on Qt 4.5.1 in production; and component is running on Qt 4.7.4. Yet I need the behaviors in the overlapping code to be the same; without having to worry about getting the compilations right in both cases.

Ben