Union in Plasma 6.7

[Nate Graham]

I'd use plasma-integration to turn it on by default for Breeze QStyle 
users in the beta release; this kind of thing is what open betas are 
for, after all.

To facilitate it, we should publish *extremely clear* information and 
instructions in the beta release announcement about what's going on, 
where to report bugs, and how to turn it off.

Then I'd say we can evaluate based on feedback received during the beta 
whether to keep it on for the general release of Plasma 6.7.

Nate




On 5/1/26 4:42 AM, Arjen Hiemstra wrote:
> Hi,
> 
> With Plasma 6.7 we will have a release of Union, the new style engine that
> we've been working on for a while now. The current state is that we have a
> fully implemented QtQuick Controls style along with a Breeze reimplementation
> in CSS. Some of us have been daily driving it for a while now and while there
> are regressions, most of these are to the extent of slightly different paddings
> or mismatching colors.
> 
> However, we cannot test all applications out there on our own, so we may have
> missed things. We really need more testing to figure out if there is major
> breakage and if so, how things break.
> 
> This isn't really possible without a more general rollout of Union, so we had
> some discussion yesterday about what exactly we want to do for 6.7. I think
> there have been three options floated about:
> 
> - We switch the default QtQuick Controls style. Since only Breeze is currently
> implemented in Union, switching it without some fallback would annoy people
> who don't use Breeze QtWidgets, so the current idea is to only use it when the
> user has selected Breeze. The main drawback is that there's no simple escape
> hatch for if an application does break to such and extent that it is unusable.
> 
> - We add an option somewhere for users to opt in using Union. The advantage is
> that this could be fully opt-in. It could also explain more about what it is
> and what the state of things is in UI. The disadvantage is that for most users
> it is going to be a meaningless option that they won't fully know what the
> implications are, since it's mainly a technical option.
> 
> - We do not do anything and rely on users setting `QT_QUICK_CONTROLS_STYLE` to
> Union. This I think is the worst outcome, as it makes it quite unlikely that
> many people use it, which means we don't get the testing coverage for Union
> that we need at this point.
> 
> I know this discussion should have been started sooner, but the soft freeze
> date kinda snuck up on me, so here we are.
> 
> - Arjen
> 
>