Fix adopting hotcue button color

[daschuer]

This fixes #12778

[ronso0]

This should go to 2.4

I don't understand why we didn't see this earlier. I did a lot of test for #12733

[ronso0]

I'd like to understand what exactly went wrong, but I don't have time atm.
@daschuer could you give a brief summary before we merge?
Shall we add a hotcue color test?

[daschuer]

Sorry, I have not tested you latest changes after my suggestions. They have introduced more checks regarding color changes via CO, like if the hotcue exists exists in slotHotcueColorChangeRequest()
When creating a new cue, the color and all properties are set before it is created, to avoid a glitch with a cue point with default values. This PR bypasses these checks in slotHotcueColorChangeRequest().

[ronso0]

Thank you, this fix LGTM.

However, I have a feeling we're working around flaws in CueControl.

FWIW the calls when setting a new hotcue are these (no guarantee for completeness):

hotcueSet
hotcueClear
  -> !pCue, return
trackCuesUpdated
loadCuesFromTrack
  -> hotcue 4
  -> pOldCue != pCue
attachCue
(detachCue)
setCue
  -> setColor #ff8000
  -> slotHotcueColorChangeRequest #ff8000
    -> !m_pCue, return
  -> set m_pCue
(detachCue for all cue controls)
attachCue
detachCue 4
resetCue 4
setCue
  -> setColor #ff8000
  -> slotHotcueColorChangeRequest #ff8000
    -> !m_pCue, return
  -> set m_pCue
setHotcueFocusIndex 3
setHotcueFocusIndex 3
setHotcueFocusIndex 3