src/vs/workbench/browser/parts/activitybar/activitybarPart.ts/ActivitybarPart/layout
class ActivitybarPart:	override layout(width: number, height: number): void {
		if (!this.layoutService.isVisible(Parts.ACTIVITYBAR_PART)) {
			return;
		}

		// Layout contents
		const contentAreaSize = super.layoutContents(width, height).contentSize;

		// Layout composite bar
		let availableHeight = contentAreaSize.height;
		if (this.menuBarContainer) {
			availableHeight -= this.menuBarContainer.clientHeight;
		}
		if (this.globalActivityActionBar) {
			availableHeight -= (this.globalActivityActionBar.viewItems.length * ActivitybarPart.ACTION_HEIGHT); // adjust height for global actions showing
		}
		this.compositeBar.layout(new Dimension(width, availableHeight));
	}