src/vs/workbench/contrib/files/browser/views/openEditorsView.ts/OpenEditorsDragAndDrop/drop
class OpenEditorsDragAndDrop:	drop(data: IDragAndDropData, targetElement: OpenEditor | IEditorGroup | undefined, _targetIndex: number, originalEvent: DragEvent): void {
		const group = targetElement instanceof OpenEditor ? targetElement.group : targetElement || this.editorGroupService.groups[this.editorGroupService.count - 1];
		const index = targetElement instanceof OpenEditor ? targetElement.group.getIndexOfEditor(targetElement.editor) : 0;

		if (data instanceof ElementsDragAndDropData) {
			const elementsData = data.elements;
			elementsData.forEach((oe: OpenEditor, offset) => {
				oe.group.moveEditor(oe.editor, group, { index: index + offset, preserveFocus: true });
			});
			this.editorGroupService.activateGroup(group);
		} else {
			this.dropHandler.handleDrop(originalEvent, () => group, () => group.focus(), index);
		}
	}