diff --git a/src/servers/app/Layer.cpp b/src/servers/app/Layer.cpp
index aeea253d32..df6d3261cb 100644
--- a/src/servers/app/Layer.cpp
+++ b/src/servers/app/Layer.cpp
@@ -557,7 +557,13 @@ void Layer::RequestDraw(const BRegion &reg, Layer *startFrom)
 
 				if (fUpdateReg.CountRects() > 0)
 				{
-					SendUpdateMsg();
+					if (!fOwner->fInUpdate)
+					{
+						fOwner->prevInvalid = fUpdateReg;
+						SendUpdateMsg();
+					}
+					else
+						fOwner->zUpdateReg.Include(&fUpdateReg);
 				}
 				
 				// we're not that different than other. We too have an
@@ -657,9 +663,9 @@ void Layer::UpdateStart()
 	fInUpdate = true;
 	if (fClassID == AS_WINBORDER_CLASS)
 	{
+		// NOTE: don't worry, RooLayer is locked here.
 		WinBorder	*wb = (WinBorder*)this;
-		wb->yUpdateReg = wb->zUpdateReg;
-		wb->zUpdateReg.MakeEmpty();
+		wb->yUpdateReg = wb->prevInvalid;
 	}
 	fClipReg = &fUpdateReg;
 }
@@ -672,6 +678,15 @@ void Layer::UpdateEnd()
 	{
 		WinBorder	*wb = (WinBorder*)this;
 		wb->yUpdateReg.MakeEmpty();
+		wb->zUpdateReg.Exclude(&wb->prevInvalid);
+		if (wb->zUpdateReg.CountRects() > 0)
+		{
+			wb->prevInvalid = wb->zUpdateReg;
+			fUpdateReg = wb->zUpdateReg;
+			SendUpdateMsg();
+		}
+		else
+			wb->prevInvalid.MakeEmpty();
 	}
 
 	fInUpdate = false;
diff --git a/src/servers/app/ServerWindow.cpp b/src/servers/app/ServerWindow.cpp
index fcc838a298..4b60457d2a 100644
--- a/src/servers/app/ServerWindow.cpp
+++ b/src/servers/app/ServerWindow.cpp
@@ -1416,7 +1416,9 @@ void ServerWindow::DispatchMessage(int32 code, LinkMsgReader &link)
 		case AS_END_UPDATE:
 		{
 			DTRACE(("ServerWindowo %s: AS_END_UPDATE\n",fTitle.String()));
+			fWinBorder->GetRootLayer()->Lock();
 			cl->UpdateEnd();
+			fWinBorder->GetRootLayer()->Unlock();
 			break;
 		}
 
@@ -1649,7 +1651,7 @@ void ServerWindow::DispatchGraphicsMessage(int32 code, LinkMsgReader &link)
 {
 	fWinBorder->GetRootLayer()->Lock();
 	BRegion		rreg(cl->fVisible);
-	rreg.Include(&fWinBorder->zUpdateReg);
+	rreg.Include(&fWinBorder->yUpdateReg);
 
 	desktop->GetDisplayDriver()->ConstrainClippingRegion(&rreg);
 
diff --git a/src/servers/app/WinBorder.h b/src/servers/app/WinBorder.h
index 31e7ba6e3d..d2367e46c9 100644
--- a/src/servers/app/WinBorder.h
+++ b/src/servers/app/WinBorder.h
@@ -114,6 +114,7 @@ protected:
 
 	BRegion	 zUpdateReg;
 	BRegion	 yUpdateReg;
+	BRegion  prevInvalid;
 
 	int32 fMouseButtons;
 	int32 fKeyModifiers;