@Fairphone_CM, that’s untrue (at least, with com.android.internal.systemui.navbar.threebutton selected):

12-23 15:51:39.893 4505 5698 D OverviewCommandHelper: the pending command queue is full (3). command not added: 4 12-23 15:51:39.895 1851 3151 V WifiDialogManager: Received action: android.intent.action.CLOSE_SYSTEM_DIALOGS 12-23 15:51:39.895 1851 3151 V WifiDialogManager: ACTION_CLOSE_SYSTEM_DIALOGS received, cancelling all legacy dialogs. 12-23 15:51:39.900 3274 3274 I vol.VolumeDialogImpl: mDialog.dismiss() reason: volume_controller from: com.android.systemui.volume.VolumeDialogImpl$7.onDismissRequested:3
Considering that issuetracker.google.com/issues/204650736 remains ASSIGNED, it couldn’t be true.