Skins :: separate play button / play_indicator + related improvements

[ronso0]

This aims to prevent update issues with play / play_indicator buttons when using blinking Cue modes (see #2342 (comment) and below): the Play buttons would sometimes not update correctly because they had 3 connections attached (play, play_indicator, cue_xx)
Also they blinked like pressed / unpressed in LateNight which was confusing, or at least inconsistent.

Furthermore this unifies the Sampler play buttons.

• Decks' Play button connections are now separated:

• top Layer is the actual button with play(left click) and cue_set (right click) connection
• bottom layer has the play_indicator connection, used to signal Cue mode blinking and previewing from Cue/hotcues

• remove the play_indicator connection from samplers' Play button:
  IMO it's distracting to have loaded samplers blink all the time with blinking Cue modes
• set Play right-click in mini decks to cue_default in all skins to have a way to return to the Cue point. Overview hotcue icons, play and cue_default suffice to prepare a deck; for more detailed preparation we have the regular decks & waveforms
• sampler Play buttons should all use a Pause icon when playing
• add play_cue_default tooltip, use it for minimal decks' Play button

Idea:

• in Shade the sampler buttons in the deck row could use an indictator to signal the sampler is loaded (in other skins the sample title is an sufficient indicator)

[ronso0]

@Be-ing Could you please try to reproduce the indicator update hickups with this branch?

[Be-ing]

Hmm, this is an interesting hack but I suspect there is a bug in WPushButton or in the engine's handling of play or play_handling at the root of this...

[ronso0]

yeah, but maybe it's simply indicator confusion for buttons with two connections affecting the displayValue. now the Play button has only one connnection.

[Holzhaus]

This now conflicts with master.

[ronso0]

Conflicts resolved.

[Holzhaus]

@Be-ing Does this fix the issue for you? Shall we merge?

[daschuer]

It looks like this PR works around a widget bug. I am struggling to follow the discussion and understand what is the main issue fixed by the stacked layout.

I like to dig for the root cause.

Can you add a step by step guide, what to do to reproduce the issue, what is shown,
what should be shown instead.

[ronso0]

I can't reproduce this anymore, just experinced this once.
@Be-ing noticed this with Numark mode IIRC: deck paused, Cue & Play blink, press Play #2342 (comment)

However, the changes proposed here solve some styling issues:
The blinking Play button (deck paused) would show the Pause icon in Deere & LateNight which is wrong and confusing. Also in LateNight the Play button would appear pressed when blinking, which is also wrong.

So I recommend to merge this regardless of the CO issue.

[daschuer]

LGTM, issue in Deere with toggling play and pause icon is fixed.

[daschuer]

@Be-ing Does this fix https://bugs.launchpad.net/mixxx/+bug/1856937 for you?

[daschuer]

Does this also fix https://bugs.launchpad.net/mixxx/+bug/1855620