Add support for solo-ing groups

src/core/rendering/reactor.cpp

@@ -221,6 +221,30 @@ void Reactor::toggleSolo(ID channelId)
 
 	ch.setSolo(newSolo);
 
+	if (ch.type == ChannelType::GROUP)
+	{
+		/* Toggling a solo on a group will toggle solo on all its children too. */
+		for (const ID childId : ch.groupChannel->getChildren())
+			m_model.get().channels.get(childId).setSolo(newSolo);
+	}
+	else if (ch.isGrouped())
+	{
+		const auto noChildrenSoloed = [this](const std::vector<ID>& childrenIds)
+		{
+			for (const ID childId : childrenIds)
+				if (m_model.get().channels.get(childId).isSoloed())
+					return false;
+			return true;
+		};
+		/* Turn parent solo on if one of the children has been soloed. Turn parent solo off
+		if no children are soloed instead. */
+		Channel& parent = m_model.get().channels.get(ch.parentId);
+		if (newSolo)
+			parent.setSolo(true);
+		else if (noChildrenSoloed(parent.groupChannel->getChildren()))
+			parent.setSolo(false);
+	}
+
 	m_model.swap(model::SwapType::SOFT);
 
 	if (ch.midiLightning.enabled)