correct highlighting of hidden tabs in single-row layout

platform/platform-api/src/com/intellij/ui/tabs/impl/JBTabsImpl.java

@@ -544,7 +544,7 @@ public class JBTabsImpl extends JComponent
       final JCheckBoxMenuItem item = new JCheckBoxMenuItem(each.getText());
       Color color = UIManager.getColor("MenuItem.background");
       if (color != null) {
-        if (lastLayout.toDrop.contains(each)) {
+        if (mySingleRowLayout.isTabHidden(each)) {
           color = new Color((int) (color.getRed() * 0.85f), (int) (color.getGreen() * 0.85f), (int) (color.getBlue() * 0.85f));
         }
 

platform/platform-api/src/com/intellij/ui/tabs/impl/singleRow/ScrollableSingleRowLayout.java

@@ -19,6 +19,7 @@ import com.intellij.ui.tabs.TabInfo;
 import com.intellij.ui.tabs.impl.JBTabsImpl;
 import com.intellij.ui.tabs.impl.TabLabel;
 
+import java.awt.*;
 import java.util.List;
 
 /**
@@ -112,4 +113,11 @@ public class ScrollableSingleRowLayout extends SingleRowLayout {
     label.setActionPanelVisible(true);
     return super.applyTabLayout(data, label, length, deltaToFit);
   }
+
+  @Override
+  public boolean isTabHidden(TabInfo tabInfo) {
+    final TabLabel label = myTabs.myInfo2Label.get(tabInfo);
+    final Rectangle bounds = label.getBounds();
+    return getStrategy().getMinPosition(bounds) < 0 || bounds.isEmpty();
+  }
 }

platform/platform-api/src/com/intellij/ui/tabs/impl/singleRow/SingleRowLayout.java

@@ -339,6 +339,10 @@ public class SingleRowLayout extends TabLayout {
   }
 
 
+  public boolean isTabHidden(TabInfo tabInfo) {
+    return myLastSingRowLayout.toDrop.contains(tabInfo);
+  }
+
   public class GhostComponent extends JLabel {
     private TabInfo myInfo;
 

platform/platform-api/src/com/intellij/ui/tabs/impl/singleRow/SingleRowLayoutStrategy.java

@@ -41,6 +41,8 @@ public abstract class SingleRowLayoutStrategy {
 
   public abstract int getLengthIncrement(final Dimension dimension);
 
+  public abstract int getMinPosition(final Rectangle bounds);
+
   public abstract int getMaxPosition(final Rectangle bounds);
 
   protected abstract int getFixedFitLength(final SingleRowPassInfo data);
@@ -106,6 +108,11 @@ public abstract class SingleRowLayoutStrategy {
       return myTabs.isEditorTabs() ? labelPrefSize.width < MIN_TAB_WIDTH ? MIN_TAB_WIDTH : labelPrefSize.width : labelPrefSize.width;
     }
 
+    @Override
+    public int getMinPosition(Rectangle bounds) {
+      return (int)bounds.getX();
+    }
+
     public int getMaxPosition(final Rectangle bounds) {
       return (int)bounds.getMaxX();
     }
@@ -266,6 +273,11 @@ public abstract class SingleRowLayoutStrategy {
       return labelPrefSize.height;
     }
 
+    @Override
+    public int getMinPosition(Rectangle bounds) {
+      return (int) bounds.getMinY();
+    }
+
     public int getMaxPosition(final Rectangle bounds) {
       int maxY = (int)bounds.getMaxY();
       return myTabs.isEditorTabs() ? maxY - 1 : maxY;