src/vs/workbench/api/browser/mainThreadEditorTabs.ts/MainThreadEditorTabs/_onDidTabActiveChange
class MainThreadEditorTabs:	private _onDidTabActiveChange(groupId: number, editorIndex: number) {
		// TODO @lramos15 use the tab lookup here if possible. Do we have an editor input?!
		const tabs = this._groupLookup.get(groupId)?.tabs;
		if (!tabs) {
			return;
		}
		const activeTab = tabs[editorIndex];
		// No need to loop over as the exthost uses the most recently marked active tab
		activeTab.isActive = true;
		// Send DTO update to the exthost
		this._proxy.$acceptTabOperation({
			groupId,
			index: editorIndex,
			tabDto: activeTab,
			kind: TabModelOperationKind.TAB_UPDATE
		});

	}