move X11 transients to top on parent top

src/Compositor.cpp

@@ -904,12 +904,35 @@ void CCompositor::moveWindowToTop(CWindow* pWindow) {
     if (!windowValidMapped(pWindow))
         return;
 
+    auto moveToTop = [&](CWindow* pw) -> void {
         for (auto it = m_vWindows.begin(); it != m_vWindows.end(); ++it) {
-        if (it->get() == pWindow) {
+            if (it->get() == pw) {
                 std::rotate(it, it + 1, m_vWindows.end());
                 break;
             }
         }
+    };
+
+    moveToTop(pWindow);
+
+    if (!pWindow->m_bIsX11)
+        return;
+
+    // move all children
+
+    std::deque<CWindow*> toMove;
+
+    for (auto& w : m_vWindows) {
+        if (w->m_bIsMapped && w->m_bMappedX11 && !w->m_bHidden && w->m_bIsX11 && w->X11TransientFor() == pWindow) {
+            toMove.emplace_back(w.get());
+        }
+    }
+
+    for (auto& pw : toMove) {
+        moveToTop(pw);
+
+        moveWindowToTop(pw);
+    }
 }
 
 void CCompositor::cleanupFadingOut(const int& monid) {

src/Window.cpp

@@ -217,3 +217,19 @@ void CWindow::moveToWorkspace(int workspaceID) {
         } 
     }
 }
+
+CWindow* CWindow::X11TransientFor() {
+    if (!m_bIsX11)
+        return nullptr;
+
+    if (!m_uSurface.xwayland->parent)
+        return nullptr;
+
+    auto PPARENT = g_pCompositor->getWindowFromSurface(m_uSurface.xwayland->parent->surface);
+
+    while (PPARENT->m_uSurface.xwayland->parent) {
+        PPARENT = g_pCompositor->getWindowFromSurface(PPARENT->m_uSurface.xwayland->parent->surface);
+    }
+
+    return PPARENT;
+}

src/Window.hpp

@@ -159,4 +159,5 @@ public:
     void            updateToplevel();
     void            updateSurfaceOutputs();
     void            moveToWorkspace(int);
+    CWindow*        X11TransientFor();
 };