src/vs/workbench/browser/parts/editor/editorActions.ts/BaseCloseAllAction/groupsToClose
class BaseCloseAllAction:	protected get groupsToClose(): IEditorGroup[] {
		const groupsToClose: IEditorGroup[] = [];

		// Close editors in reverse order of their grid appearance so that the editor
		// group that is the first (top-left) remains. This helps to keep view state
		// for editors around that have been opened in this visually first group.
		const groups = this.editorGroupService.getGroups(GroupsOrder.GRID_APPEARANCE);
		for (let i = groups.length - 1; i >= 0; i--) {
			groupsToClose.push(groups[i]);
		}

		return groupsToClose;
	}