extensions/markdown-language-features/src/features/previewManager.ts/MarkdownPreviewManager/registerDynamicPreview
class MarkdownPreviewManager:	private registerDynamicPreview(preview: DynamicMarkdownPreview): DynamicMarkdownPreview {
		this._dynamicPreviews.add(preview);

		preview.onDispose(() => {
			this._dynamicPreviews.delete(preview);
		});

		this.trackActive(preview);

		preview.onDidChangeViewState(() => {
			// Remove other dynamic previews in our column
			disposeAll(Array.from(this._dynamicPreviews).filter(otherPreview => preview !== otherPreview && preview.matches(otherPreview)));
		});
		return preview;
	}