Fix ColorPicker deferred mode not working for sliders.

[ajreckof]

Fixes #80915

[KoBeWi]

Clicking the slider does not emit changed signal in deferred mode. You need to drag it at least 1 px. SpinBox is also broken (note that you can drag SpinBox too).

[KoBeWi]

It's fine now, but there is a little inconsistency. Clicking the slider for the first time emits the signal immediately, while it doesn't happen when clicking the color box/circle. This is still an improvement, so I think that small inconsistency is ok (unless you can fix it easily?).
Dragging SpinBox still emits signal continuously. SpinBox doesn't expose any drag signals though, so it can be fixed later.

[ajreckof]

It's fine now, but there is a little inconsistency. Clicking the slider for the first time emits the signal immediately, while it doesn't happen when clicking the color box/circle. This is still an improvement, so I think that small inconsistency is ok (unless you can fix it easily?).

I found it just after pushing I was looking at it. I'm not 100% sure why it is happening but should be pretty easy to fix

Dragging SpinBox still emits signal continuously. SpinBox doesn't expose any drag signals though, so it can be fixed later.

Yeah that was what I was going to say the class feels a bit lacking :(

[ajreckof]

So I fixed the slider trigerring color_changed signal at the start of dragging, and at the same time it made me realise and fix that when clicking the slider it would trigger the signal twice.

[KoBeWi]

SpinBoxes are broken in deferred mode again 🙃

[KoBeWi]

Works correctly now, left a few comments.

The Range changes make _drag_started() emitted before value changed. Probably it's fine though.

[ajreckof]

I added both of your recommendation
I'm not 100% confident on the Range change but it is needed. I'll try to be as clear as possible on the reason that lead me to this modification.
So first since the SpinBox and the Slider share the same range whenever you modify one the other is updated but also both emit the value_changed signal. This means when you receive a value_changed signal from one you don't wether it is from one or the other.
What we want to achieve is that in deferred mode only at the drag end color_changed so the easiest idea is to just prevent the emission of the signal when the value_changed signal is received and emit the signal when the drag_ended signal is received. Unfortunately because of what I said earlier this isn't possible because to prevent the emission of the signal when the value_changed is received you can't differentiate between it being emitted from one or the other, therefore you will just never emit color_changed when changing value through the SpinBox.
So the other way is to detect when you are effectively doing a drag which means between the reception of drag_started and the reception of drag_ended. This works well but unfortunately this has a secondary problem which is the first value_changed signal is emitted before the drag_started signal which in trns mean you won't be able to know it is from the drag. So I reordered them but as to reduce the change I made sure that only their order were changed. Which means I had to update the value of the slider first without emitting the value_changed signal and then first emitting drag_started and then emit the value_changed signal.

If SpinBox ever gets drag_started/drag_ended signals just connecting them to the same function will fix the drag for SpinBox too.

[akien-mga]

I see this adds more _no_signal helpers. We should aim to resolve the discussion on #76432 before adding more methods like this (though this one isn't exposed so it's not too critical).

[akien-mga]

Thanks!