src/vs/workbench/api/browser/mainThreadEditorTabs.ts/MainThreadEditorTabs/_onDidGroupActivate
class MainThreadEditorTabs:	private _onDidGroupActivate() {
		const activeGroupId = this._editorGroupsService.activeGroup.id;
		const activeGroup = this._groupLookup.get(activeGroupId);
		if (activeGroup) {
			// Ok not to loop as exthost accepts last active group
			activeGroup.isActive = true;
			this._proxy.$acceptTabGroupUpdate(activeGroup);
		}
	}