Fix: Always draw dirty blocks, else fast-forward is super fast.

src/window.cpp

@@ -3156,9 +3156,9 @@ void UpdateWindows()
 				w->SetDirty();
 			}
 		}
+	}
 
 	DrawDirtyBlocks();
-	}
 
 	FOR_ALL_WINDOWS_FROM_BACK(w) {
 		/* Update viewport only if window is not shaded. */