diff --git a/effects/sheet/sheet.cpp b/effects/sheet/sheet.cpp
--- a/effects/sheet/sheet.cpp
+++ b/effects/sheet/sheet.cpp
@@ -31,8 +31,6 @@
 namespace KWin
 {
 
-static const int IsSheetWindow = 0x22A982D5;
-
 SheetEffect::SheetEffect()
 {
     initConfig<SheetConfig>();
@@ -123,7 +121,6 @@
 {
     if (!isSheetWindow(w))
         return;
-    w->setData(IsSheetWindow, true);
 
     InfoMap::iterator it = windows.find(w);
     WindowInfo *info = (it == windows.end()) ? &windows[w] : &it.value();
@@ -181,7 +178,7 @@
 
 bool SheetEffect::isSheetWindow(EffectWindow* w)
 {
-    return (w->isModal() || w->data(IsSheetWindow).toBool());
+    return w->isModal();
 }
 
 bool SheetEffect::isActive() const