KDE3 apps running in a KDE4-modified environment

[Thiago Macieira]

Rex Dieter said:
> Thiago Macieira wrote:
>> Mauricio Piacentini wrote:
>>> But the potential problem exists now: what if an user
>>> installs KDE4, runs Kmahjongg 4, and then attempts to install, download
>>> and run the KDE3 version?
>>
>> You're not allowed to do that. KDE applications do NOT support
>> downgrading.
>>
>> They never have.
>
> Wouldn't such a policy prevent kde3/kde4 ever being able to be installed
> into the same prefix?  Or am I missing something?

That depends.

You are in no way allowed to downgrade applications once their config
files have been touched. That's valid for a 3.5 to 4.0 upgrade as well as
3.4 to 3.5 or 4.0 to 4.1. Especially if there's an .upd script.

However, there are some shared config files (like kdeglobals) that we have
to check for backwards compatibility before the 4.0 release. Those files
should never be the target of an .upd script.

We don't have it yet, but we could have a KDE4HOME variable that overrides
KDEHOME for KDE 4 applications. That way, you'll have two separate config
directories for your 3 and 4 applications. However, this could hinder the
upgrade, because applications will not notice the old config file (maybe
we could treat KDEHOME in the presence of KDE4HOME as just one more
KDEDIRS...)

Reactions?

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  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
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