src/vs/workbench/api/common/extHostOutput.ts/ExtHostOutputService/$setVisibleChannel
class ExtHostOutputService:	$setVisibleChannel(visibleChannelId: string | null): void {
		this.visibleChannelId = visibleChannelId;
		for (const [id, channel] of this.channels) {
			channel.visible = id === this.visibleChannelId;
		}
	}