diff --git a/src/tse/lr5/PaintPanel.java b/src/tse/lr5/PaintPanel.java
index 0d6b22b..cd5c618 100644
--- a/src/tse/lr5/PaintPanel.java
+++ b/src/tse/lr5/PaintPanel.java
@@ -4,8 +4,10 @@ import java.awt.Color;
 import java.awt.Dimension;
 import java.awt.Graphics;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import javax.swing.JPanel;
+import javax.swing.SwingUtilities;
 
 /**
  * Панель рисования.
@@ -16,7 +18,7 @@ public class PaintPanel extends JPanel {
     private final List<PaintableObject> paintables;
     
     public PaintPanel(int width, int height) {
-        paintables = new ArrayList<>();
+        paintables = Collections.synchronizedList(new ArrayList<PaintableObject>());
         
         setBackground(Color.WHITE);
         setPreferredSize(new Dimension(width, height));
@@ -24,7 +26,13 @@ public class PaintPanel extends JPanel {
     
     public synchronized void addPaintable(PaintableObject obj) {
         paintables.add(obj);
-        invalidate();
+        SwingUtilities.invokeLater(new Runnable() {
+
+            @Override
+            public void run() {
+                repaint();
+            }
+        });
     }
 
     @Override