Implement isBuilding() to show the flashing orb from the start.

src/main/java/com/etsy/jenkins/MasterBuild.java

@@ -6,29 +6,24 @@
 import hudson.model.AbstractProject;
 import hudson.model.Build;
 import hudson.model.Cause;
-import hudson.model.Hudson;
-import hudson.model.Item;
 import hudson.model.Result;
-import hudson.model.Run;
 import hudson.security.Permission;
 
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
 
 import com.google.common.collect.Lists;
-import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
 import java.io.File;
 import java.io.IOException;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
-import java.util.SortedSet;
 import java.util.concurrent.Future;
 import javax.servlet.ServletException;
+import org.kohsuke.stapler.HttpResponse;
 
 public class MasterBuild extends Build<MasterProject, MasterBuild> {
 
@@ -106,6 +101,15 @@ public Result getResult() {
     return result;
   }
 
+  @Override
+  public boolean isBuilding() {
+    if (super.isBuilding()) {
+      // If this build's executor is running, defer to that.
+      return true;
+    }
+    return this.masterResult.isBuilding();
+  }
+
   /*package*/ void addSubBuild(String projectName, int buildNumber) {
     masterResult.addBuild(projectName, buildNumber);
 
@@ -124,7 +128,7 @@ public List<AbstractBuild> getLatestBuilds() {
   public void rebuild(AbstractProject project) throws ServletException {
     if (!getSubProjects().contains(project)) {
         throw new ServletException(
-            "Not a sub-project of this master build: " 
+            "Not a sub-project of this master build: "
             + project.getDisplayName());
     }
 
@@ -150,12 +154,12 @@ public void doRefreshLatestBuilds(StaplerRequest req, StaplerResponse res)
   }
 
   @Override
-  public void doStop(StaplerRequest req, StaplerResponse res) 
+  public HttpResponse doStop()
       throws IOException, ServletException {
     for (Future<AbstractBuild> future : futuresToAbort) {
       future.cancel(true);
     }
-    super.doStop(req, res);
+    return super.doStop();
   }
 }
 

src/main/java/com/etsy/jenkins/MasterResult.java

@@ -66,5 +66,18 @@ public Result getOverallResult() {
     }
     return endResult;
   }
+
+  public boolean isBuilding() {
+    if (results.isEmpty()) {
+      // No builds have been scheduled yet.
+      return true;
+    }
+    for (SubResult subResult : results.values()) {
+      if (subResult.getLatestBuild().isBuilding()) {
+        return true;
+      }
+    }
+    return false;
+  }
 }