Bug 53582 Rebuild Project are not run in the background?
The "Build All" and "Rebuild All" actions are run in the background, but the "Build Project" and "Rebuild Project" actions aren't. This is not consistent and I was surprised to get a modal dialog when performing a "Rebuild Project".
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/WorkspaceAction.java
if (shouldPerformResourcePruning()) {
			resources = pruneResources(resources);
		}
		Iterator resourcesEnum = resources.iterator();
		
		monitor.beginTask("", resources.size() * 1000); 
		
		
		
		
		monitor.setTaskName(getOperationMessage());
		try {
			while (resourcesEnum.hasNext()) {
				IResource resource = (IResource) resourcesEnum.next();
				try {
					
					invokeOperation(resource, new SubProgressMonitor(monitor, 1000));
				} catch (CoreException e) {
					recordError(e);
				}
				if (monitor.isCanceled())
					throw new OperationCanceledException();
			}
		} finally {
			monitor.done();
		}
	}
	/**
	 * Returns the string to display for this action's operation.
	 * <p>