We are using TMS FNC WX Pack 1.7.1.1 and found an issue in the method TTMSFNCWXCustomHTMLMemo.DoHandleInit which sets the CSS height property not only for contained elements of this HTMLMemo instance, but for all elements in the DOM matching the CSS classes passed to document.querySelectorAll. We fixed that by adding the following check in each loop iterating the querySelectorAll result:
if Self.ElementHandle.contains(Element) then