src/vs/workbench/browser/actions/layoutActions.ts/BaseResizeViewAction/resizePart
class BaseResizeViewAction:	protected resizePart(widthChange: number, heightChange: number, layoutService: IWorkbenchLayoutService, partToResize?: Parts): void {

		let part: Parts | undefined;
		if (partToResize === undefined) {
			const isEditorFocus = layoutService.hasFocus(Parts.EDITOR_PART);
			const isSidebarFocus = layoutService.hasFocus(Parts.SIDEBAR_PART);
			const isPanelFocus = layoutService.hasFocus(Parts.PANEL_PART);
			const isAuxiliaryBarFocus = layoutService.hasFocus(Parts.AUXILIARYBAR_PART);

			if (isSidebarFocus) {
				part = Parts.SIDEBAR_PART;
			} else if (isPanelFocus) {
				part = Parts.PANEL_PART;
			} else if (isEditorFocus) {
				part = Parts.EDITOR_PART;
			} else if (isAuxiliaryBarFocus) {
				part = Parts.AUXILIARYBAR_PART;
			}
		} else {
			part = partToResize;
		}

		if (part) {
			layoutService.resizePart(part, widthChange, heightChange);
		}
	}