diff --color -ruN a/xembed-sni-proxy/sniproxy.cpp b/xembed-sni-proxy/sniproxy.cpp
--- a/xembed-sni-proxy/sniproxy.cpp	2026-10-04 00:25:26.299757174 +0200
+++ b/xembed-sni-proxy/sniproxy.cpp	2026-10-04 00:25:26.319273269 +0200
@@ -525,6 +525,13 @@
     const auto title = Title();
     // we always need /some/ ID so if no window title exists, just use the winId.
     if (title.isEmpty()) {
+        // Prefer the window class: unlike the winId it is the same on every launch,
+        // so trays can match on it (Wine leaves the title of its tray windows empty).
+        const KWindowInfo window(m_windowId, NET::Properties(), NET::WM2WindowClass);
+        const QByteArray windowClass = window.windowClassClass();
+        if (!windowClass.isEmpty()) {
+            return QString::fromUtf8(windowClass);
+        }
         return QString::number(m_windowId);
     }
     return title;