src/vs/editor/contrib/hover/hoverWidgets.ts/GlyphHoverWidget/showAt
class GlyphHoverWidget:	public showAt(lineNumber: number): void {
		this._showAtLineNumber = lineNumber;

		if (!this.isVisible) {
			this.isVisible = true;
		}

		const editorLayout = this._editor.getLayoutInfo();
		const topForLineNumber = this._editor.getTopForLineNumber(this._showAtLineNumber);
		const editorScrollTop = this._editor.getScrollTop();
		const lineHeight = this._editor.getOption(EditorOption.lineHeight);
		const nodeHeight = this._domNode.clientHeight;
		const top = topForLineNumber - editorScrollTop - ((nodeHeight - lineHeight) / 2);

		this._domNode.style.left = `${editorLayout.glyphMarginLeft + editorLayout.glyphMarginWidth}px`;
		this._domNode.style.top = `${Math.max(Math.round(top), 0)}px`;
	}