src/vs/workbench/contrib/terminal/browser/terminalGroupService.ts/TerminalGroupService/setActiveGroupToPrevious
class TerminalGroupService:	setActiveGroupToPrevious() {
		if (this.groups.length <= 1) {
			return;
		}
		let newIndex = this.activeGroupIndex - 1;
		if (newIndex < 0) {
			newIndex = this.groups.length - 1;
		}
		this.setActiveGroupByIndex(newIndex);
	}