src/vs/workbench/browser/layout.ts/Layout/setAuxiliaryBarHidden
class Layout:	private setAuxiliaryBarHidden(hidden: boolean, skipLayout?: boolean): void {
		this.stateModel.setRuntimeValue(LayoutStateKeys.AUXILIARYBAR_HIDDEN, hidden);

		// Adjust CSS
		if (hidden) {
			this.container.classList.add(WorkbenchLayoutClasses.AUXILIARYBAR_HIDDEN);
		} else {
			this.container.classList.remove(WorkbenchLayoutClasses.AUXILIARYBAR_HIDDEN);
		}

		// If auxiliary bar becomes hidden, also hide the current active pane composite if any
		if (hidden && this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
			this.paneCompositeService.hideActivePaneComposite(ViewContainerLocation.AuxiliaryBar);

			// Pass Focus to Editor or Panel if Auxiliary Bar is now hidden
			const activePanel = this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.Panel);
			if (this.hasFocus(Parts.PANEL_PART) && activePanel) {
				activePanel.focus();
			} else {
				this.focus();
			}
		}

		// If auxiliary bar becomes visible, show last active pane composite or default pane composite
		else if (!hidden && !this.paneCompositeService.getActivePaneComposite(ViewContainerLocation.AuxiliaryBar)) {
			let panelToOpen: string | undefined = this.paneCompositeService.getLastActivePaneCompositeId(ViewContainerLocation.AuxiliaryBar);

			// verify that the panel we try to open has views before we default to it
			// otherwise fall back to any view that has views still refs #111463
			if (!panelToOpen || !this.hasViews(panelToOpen)) {
				panelToOpen = this.viewDescriptorService
					.getViewContainersByLocation(ViewContainerLocation.AuxiliaryBar)
					.find(viewContainer => this.hasViews(viewContainer.id))?.id;
			}

			if (panelToOpen) {
				const focus = !skipLayout;
				this.paneCompositeService.openPaneComposite(panelToOpen, ViewContainerLocation.AuxiliaryBar, focus);
			}
		}

		// Propagate to grid
		this.workbenchGrid.setViewVisible(this.auxiliaryBarPartView, !hidden);
	}