diff --git a/effects/sheet/sheet.cpp b/effects/sheet/sheet.cpp
--- a/effects/sheet/sheet.cpp
+++ b/effects/sheet/sheet.cpp
@@ -137,6 +137,9 @@
             break;
         }
     }
+
+    w->setData(WindowAddedGrabRole, QVariant::fromValue(static_cast<void*>(this)));
+
     w->addRepaintFull();
 }
 
@@ -168,6 +171,9 @@
     }
     if (!found)
         info->parentY = 0;
+
+    w->setData(WindowClosedGrabRole, QVariant::fromValue(static_cast<void*>(this)));
+
     w->addRepaintFull();
 }