fixes #40674

src/vs/base/browser/htmlContentRenderer.ts

@@ -18,6 +18,7 @@ export interface RenderOptions {
 	inline?: boolean;
 	actionCallback?: (content: string, event?: IMouseEvent) => void;
 	codeBlockRenderer?: (modeId: string, value: string) => string | Thenable<string>;
+	codeBlockRenderCallback?: () => void;
 }
 
 function createElement(options: RenderOptions): HTMLElement {
@@ -126,7 +127,7 @@ export function renderMarkdown(markdown: IMarkdownString, options: RenderOptions
 				// when code-block rendering is async we return sync
 				// but update the node with the real result later.
 				const id = defaultGenerator.nextId();
-				Promise.all([value, withInnerHTML]).then(values => {
+				const promise = Promise.all([value, withInnerHTML]).then(values => {
 					const strValue = values[0] as string;
 					const span = element.querySelector(`div[data-code="${id}"]`);
 					if (span) {
@@ -135,6 +136,11 @@ export function renderMarkdown(markdown: IMarkdownString, options: RenderOptions
 				}).catch(err => {
 					// ignore
 				});
+
+				if (options.codeBlockRenderCallback) {
+					promise.then(options.codeBlockRenderCallback);
+				}
+
 				return `<div class="code" data-code="${id}">${escape(code)}</div>`;
 			}
 

src/vs/editor/contrib/hover/hoverWidgets.ts

@@ -140,6 +140,10 @@ export class ContentHoverWidget extends Widget implements editorBrowser.IContent
 		this.updateFont();
 
 		this._editor.layoutContentWidget(this);
+		this.onContentsChange();
+	}
+
+	protected onContentsChange(): void {
 		this.scrollbar.scanDomNode();
 	}
 

src/vs/editor/contrib/hover/modesContentHover.ts

@@ -167,15 +167,17 @@ export class ModesContentHoverWidget extends ContentHoverWidget {
 	private _colorPicker: ColorPickerWidget;
 
 	private renderDisposable: IDisposable = EmptyDisposable;
-	private toDispose: IDisposable[];
+	private toDispose: IDisposable[] = [];
 
 	constructor(editor: ICodeEditor, markdownRenderner: MarkdownRenderer) {
 		super(ModesContentHoverWidget.ID, editor);
 
 		this._computer = new ModesContentComputer(this._editor);
 		this._highlightDecorations = [];
 		this._isChangingDecorations = false;
+
 		this._markdownRenderer = markdownRenderner;
+		markdownRenderner.onDidRenderCodeBlock(this.onContentsChange, this, this.toDispose);
 
 		this._hoverOperation = new HoverOperation(
 			this._computer,
@@ -184,7 +186,6 @@ export class ModesContentHoverWidget extends ContentHoverWidget {
 			result => this._withResult(result, false)
 		);
 
-		this.toDispose = [];
 		this.toDispose.push(dom.addStandardDisposableListener(this.getDomNode(), dom.EventType.FOCUS, () => {
 			if (this._colorPicker) {
 				dom.addClass(this.getDomNode(), 'colorpicker-hover');

src/vs/editor/contrib/markdown/markdownRenderer.ts

@@ -15,9 +15,13 @@ import { onUnexpectedError } from 'vs/base/common/errors';
 import { tokenizeToString } from 'vs/editor/common/modes/textToHtmlTokenizer';
 import { ICodeEditor } from 'vs/editor/browser/editorBrowser';
 import { optional } from 'vs/platform/instantiation/common/instantiation';
+import Event, { Emitter } from 'vs/base/common/event';
 
 export class MarkdownRenderer {
 
+	private _onDidRenderCodeBlock = new Emitter<void>();
+	readonly onDidRenderCodeBlock: Event<void> = this._onDidRenderCodeBlock.event;
+
 	private readonly _options: RenderOptions;
 
 	constructor(
@@ -42,7 +46,8 @@ export class MarkdownRenderer {
 				}).then(code => {
 					return `<span style="font-family: ${editor.getConfiguration().fontInfo.fontFamily}">${code}</span>`;
 				});
-			}
+			},
+			codeBlockRenderCallback: () => this._onDidRenderCodeBlock.fire()
 		};
 	}