diff --git a/src/kits/interface/WindowStack.cpp b/src/kits/interface/WindowStack.cpp
index 688a97f291..34db295976 100644
--- a/src/kits/interface/WindowStack.cpp
+++ b/src/kits/interface/WindowStack.cpp
@@ -163,7 +163,7 @@ BWindowStack::HasWindow(const BMessenger& window)
 	int32 code = B_ERROR;
 	fLink->FlushWithReply(code);
 	if (code != B_OK)
-		return code;
+		return false;
 
 	bool hasWindow;
 	if (fLink->Read<bool>(&hasWindow) != B_OK)
@@ -205,5 +205,6 @@ BWindowStack::_StartMessage(int32 what)
 {
 	fLink->StartMessage(AS_TALK_TO_DESKTOP_LISTENER);
 	fLink->Attach<int32>(kMagicSATIdentifier);
+	fLink->Attach<int32>(kStacking);
 	return fLink->Attach<int32>(what);
 }
diff --git a/src/servers/app/Desktop.cpp b/src/servers/app/Desktop.cpp
index 2fc0a6349a..7baf5bc41d 100644
--- a/src/servers/app/Desktop.cpp
+++ b/src/servers/app/Desktop.cpp
@@ -2643,7 +2643,7 @@ Desktop::AllWindows()
 Window*
 Desktop::WindowForClientLooperPort(port_id port)
 {
-	ASSERT(fWindowLock.IsReadLocked());
+	ASSERT_MULTI_LOCKED(fWindowLock);
 
 	for (Window* window = fAllWindows.FirstWindow(); window != NULL;
 			window = window->NextWindow(kAllWindowList)) {