update gutter icon for related file when related items are changed

platform/lang-api/src/com/intellij/codeInsight/daemon/LineMarkerInfo.java

@@ -35,7 +35,7 @@ import java.awt.event.MouseEvent;
 import java.lang.ref.WeakReference;
 
 public class LineMarkerInfo<T extends PsiElement> {
-  private final Icon myIcon;
+  protected final Icon myIcon;
   private final WeakReference<T> elementRef;
   public final int startOffset;
   public final int endOffset;
@@ -157,7 +157,7 @@ public class LineMarkerInfo<T extends PsiElement> {
       return myInfo.myIconAlignment;
     }
 
-    private boolean looksTheSameAs(@NotNull LineMarkerGutterIconRenderer renderer) {
+    protected boolean looksTheSameAs(@NotNull LineMarkerGutterIconRenderer renderer) {
       return
         myInfo.getElement() != null &&
         renderer.myInfo.getElement() != null &&

platform/lang-api/src/com/intellij/codeInsight/daemon/RelatedItemLineMarkerInfo.java

@@ -60,4 +60,27 @@ public class RelatedItemLineMarkerInfo<T extends PsiElement> extends LineMarkerI
   public Collection<? extends GotoRelatedItem> createGotoRelatedItems() {
     return myTargets.getValue();
   }
+
+  @Override
+  public GutterIconRenderer createGutterRenderer() {
+    if (myIcon == null) return null;
+    return new RelatedItemLineMarkerGutterIconRenderer<T>(this);
+  }
+
+  private static class RelatedItemLineMarkerGutterIconRenderer<T extends PsiElement> extends LineMarkerGutterIconRenderer<T> {
+    public RelatedItemLineMarkerGutterIconRenderer(final RelatedItemLineMarkerInfo<T> markerInfo) {
+      super(markerInfo);
+    }
+
+    @Override
+    protected boolean looksTheSameAs(@NotNull LineMarkerGutterIconRenderer renderer) {
+      if (!(renderer instanceof RelatedItemLineMarkerGutterIconRenderer) || !super.looksTheSameAs(renderer)) {
+        return false;
+      }
+
+      final RelatedItemLineMarkerInfo<?> markerInfo = (RelatedItemLineMarkerInfo<?>)getLineMarkerInfo();
+      final RelatedItemLineMarkerInfo<?> otherInfo = (RelatedItemLineMarkerInfo<?>)renderer.getLineMarkerInfo();
+      return markerInfo.myTargets.equals(otherInfo.myTargets);
+    }
+  }
 }