diff --git a/platform/platform-api/src/com/intellij/util/ui/ButtonlessScrollBarUI.java b/platform/platform-api/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
index 704dfcde5001..b11ca7f3222f 100644
--- a/platform/platform-api/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
+++ b/platform/platform-api/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
@@ -223,10 +223,10 @@ public class ButtonlessScrollBarUI extends BasicScrollBarUI {
   }
 
   public int getDecrementButtonHeight() {
-    return decrButton.getHeight();
+    return Math.max(0, decrButton.getHeight());
   }
   public int getIncrementButtonHeight() {
-    return incrButton.getHeight();
+    return Math.max(0, incrButton.getHeight());
   }
 
   private void resetRegularThumbAnimator() {
diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
index 21d527b1fff5..51f6ec4a8cdb 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java
@@ -4822,22 +4822,21 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     int getDecScrollButtonHeight() {
       ScrollBarUI barUI = getUI();
       Insets insets = getInsets();
+      int top = Math.max(0, insets.top);
       if (barUI instanceof ButtonlessScrollBarUI) {
-        return insets.top + ((ButtonlessScrollBarUI)barUI).getDecrementButtonHeight();
+        return top + ((ButtonlessScrollBarUI)barUI).getDecrementButtonHeight();
       }
-      else if (barUI instanceof BasicScrollBarUI) {
+      if (barUI instanceof BasicScrollBarUI) {
         try {
           JButton decrButtonValue = (JButton)decrButtonField.get(barUI);
           LOG.assertTrue(decrButtonValue != null);
-          return insets.top + decrButtonValue.getHeight();
+          return top + decrButtonValue.getHeight();
         }
         catch (Exception exc) {
           throw new IllegalStateException(exc);
         }
       }
-      else {
-        return insets.top + 15;
-      }
+      return top + 15;
     }
 
     /**
diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorMarkupModelImpl.java b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorMarkupModelImpl.java
index 1df027a8cfb0..c4602784c0a7 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorMarkupModelImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorMarkupModelImpl.java
@@ -127,9 +127,10 @@ public class EditorMarkupModelImpl extends MarkupModelImpl implements EditorMark
 
   void recalcEditorDimensions() {
     EditorImpl.MyScrollBar scrollBar = myEditor.getVerticalScrollBar();
-    int scrollBarHeight = scrollBar.getSize().height;
+    int scrollBarHeight = Math.max(0, scrollBar.getSize().height);
 
     myEditorScrollbarTop = scrollBar.getDecScrollButtonHeight()/* + 1*/;
+    assert myEditorScrollbarTop>=0;
     int editorScrollbarBottom = scrollBar.getIncScrollButtonHeight();
     myEditorTargetHeight = scrollBarHeight - myEditorScrollbarTop - editorScrollbarBottom;
     myEditorSourceHeight = myEditor.getPreferredHeight();