Fix missing expand button on codeblocks

src/components/views/messages/TextualBody.tsx

@@ -136,7 +136,8 @@ export default class TextualBody extends React.Component<IBodyProps, IState> {
     private addCodeExpansionButton(div: HTMLDivElement, pre: HTMLPreElement): void {
         // Calculate how many percent does the pre element take up.
         // If it's less than 30% we don't add the expansion button.
-        const percentageOfViewport = pre.offsetHeight / UIStore.instance.windowHeight * 100;
+        // We also round the number as it sometimes can be 29.99...
+        const percentageOfViewport = Math.round(pre.offsetHeight / UIStore.instance.windowHeight * 100);
         if (percentageOfViewport < 30) return;
 
         const button = document.createElement("span");