In a nutshell, what’s supposed to happen is when you click on the web part, there will be a custom tab that appears in the Ribbon. It all works great for the first instance of the custom web part you place onto a page, but if you try adding a second instance of the web part, your page blows up!

You’ll get the following error:
Item has already been added. Key in dictionary: ‘Ribbon.CustomContextualTabGroup’ Key being added: ‘Ribbon.CustomContextualTabGroup’

:-/ … looks like there wasn’t much QA done for the walkthrough. Anyways, to make a short story shorter… I posted a question on the TechNet forums and Dallas Tester from MS did get back to me with a bunch of suggestions.

Here are the changes you can make to allow for multiple instances of the custom web part to appear on the page without everything blowing up.

Make the following modifications to the ContextualTabWebPart class.

Add the global ‘_added’ bool and OnInit event handler:

static bool _added = false;

protected override void OnInit(EventArgs e)
{
 base.OnInit(e);
 _added = false;
}

Since we no longer have to get the unique component ID in the delay script, I changed DelayScript into a private string:

private string delayScript = @"
 function _addCustomPageComponent()
 {
  for (var i = 0; i < g_customWebPartIds.length; i++)
  {
    SP.Ribbon.PageManager.get_instance().addPageComponent(new ContextualTabWebPart.CustomPageComponent(g_customWebPartIds[i]));
  }
 }

 function _registerCustomPageComponent()
 {
  SP.SOD.registerSod(""CustomContextualTabPageComponent.js"", ""/_layouts/CustomContextualTabPageComponent.js"");
  var isDefined = ""undefined"";
  try
  {
   isDefined = typeof(ContextualTabWebPart.CustomPageComponent);
  }
  catch(e)
  {
  }
  EnsureScript(""CustomContextualTabPageComponent.js"",isDefined, _addCustomPageComponent);
 }
 SP.SOD.executeOrDelayUntilScriptLoaded(_registerCustomPageComponent, ""sp.ribbon.js"");";

Modify the OnPreRender event handler:

protected override void OnPreRender(EventArgs e)
{
 base.OnPreRender(e);

 ClientScriptManager csm = this.Page.ClientScript;
 string componentId = SPRibbon.GetWebPartPageComponentId(this); // the unique component id 

 // if this is the first instance of the custom web part,
 //we need to add the contextual tab to the ribbon
 if (!_added)
 {
  this.AddContextualTab();
  _added = true;
 }

 // we need to create an array which will store the IDs of all instances of our custom web part
 csm.RegisterClientScriptBlock(
  this.GetType(), "DeclareCustomWebPartArray", "var g_customWebPartIds = new Array();", true);

 // add this webpart's ID to our array
 csm.RegisterClientScriptBlock(
  this.GetType(), "AddCustomWebPartId" + componentId, "g_customWebPartIds.push('" + componentId + "');", true);

 csm.RegisterClientScriptBlock(this.GetType(), "ContextualTabWebPart", this.delayScript, true);
}

If you want to verify that the correct web part is trigger the Ribbon commands, you can modify the ‘handleCommand‘ method in ‘CustomContextualTabPageComponent.js‘

handleCommand: function ContextualTabWebPart_CustomPageComponent$handleCommand(commandId, properties, sequence) {
 if (commandId === 'CustomContextualTab.HelloWorldCommand') {
  alert(this._webPartPageComponentId + ' says: Hello, world!');
 }
 if (commandId === 'CustomContextualTab.GoodbyeWorldCommand') {
  alert(this._webPartPageComponentId + ' says: Good-bye, world!');
 }
}

Here’s a ZIP file of the entire solution in case you’re too lazy to make the modifications yourself.

Delegate Controls

As I mentioned at the end of part two, the way we’re going to get our CSS added to our sites and pages is through the use of a delegate control. For those of you who aren’t familiar with delegate controls, they are essentially placeholders for you to inject your own controls via a feature. Your feature can be scoped to either Web, Site, WebApplication or Farm. I’m going to keep the explanation on delegate controls short as there’s plenty of information out there about them:

• Chris O’Brien: Using the Delegate Control
• SharePoint’s Delegate Control Power
• MSDN 2010 SDK: DelegateControl Class

AdditionalPageHead Delegate Control

The AdditionalPageHead Delegate

Delegate controls have a AllowMultipleControls property which when set to true, all controls keyed to that delegate are added to the page; when set to false, only the control registered with the lowest sequence value is added to the page.

All of the delegate controls in the OOTB master pages have AllowMultipleControls set to false, with the exception of one, AdditionalPageHead, which does allow multiple controls. And guess what? AdditionalPageHead is actually located in the page head, where you would normally add CSS elements! This is the perfect place for us to inject any CSS registration controls.

Putting it all together…

Let’s put together a simple solution using the Visual Studio 2010 SharePoint Tools which will:

1. deploy our CSS file in the Themable folder in the /Layouts/1033/Styles
2. deploy a user control into the ControlTemplates folder which uses the CSSRegistration control to register our CSS
3. install a feature which inserts our user control onto our pages via the AdditionalPageHead delegate

The CSS

Keeping it simple, all our CSS does is set the background color of the <body>. We’ll use #FFF (white) as our default background color and also decorate the rule with one of the SharePoint 2010 compile time directives to whatever we might set the “Light1″ color value as through the Theme UI.

body {
/*[ReplaceColor(themeColor:"Light1")]*/
background-color: #fff;
}

The Delegate Control

Again, nice and simple, we’re going to use the CSSRegistration control to register our branding CSS after corev4.css:

<%@ Assembly Name="$SharePoint.Project.AssemblyFullName$" %>
<%@ Register Tagprefix="SharePoint" Namespace="Microsoft.SharePoint.WebControls" Assembly="Microsoft.SharePoint, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

<sharepoint :CSSRegistration Name="<% $SPUrl:~sitecollection/_layouts/1033/Styles/Themable/SingChan.SP2010.Branding/branding.css %>" After="corev4.css" runat="server" />
</sharepoint>

Element Manifest

And finally we’ll define our element manifest for our delegate feature:

<?xml version="1.0" encoding="utf-8"?>
<elements xmlns="http://schemas.microsoft.com/sharepoint/">
    <control Id="AdditionalPageHead" Sequence="80" ControlSrc="~/_ControlTemplates/SingChan.SP2010.Branding/CSSRegistrationControl.ascx" />
</elements>

You’ll most likely scope your delegate feature to either Web or Site for branding purposes. I tend to scope my feature at the site collection level to achieve a consistent brand across all the webs in the site collection. If there’s a requirement to have different branding for one or two specific sites, then we can always have a second feature which deploys those overrides at a web-level scope. If you have vastly different brands across webs in your site collection, then you may want to scope only at the web level so that your brands don’t conflict or end up with any style inheritance issues.

That’s it!

If all went well, we should see the link to our style sheet emitted after the link to corev4.css!

Our branding CSS being emitted in HTML

If all is not well, here’s the ZIP file containing the branding VS2010 solution for reference:
SingChan.SP2010.Branding.zip

Previously…

• You can find Part One here!
• You can find Part Two here!

Here’s what he’s got so far:

• Extending the SharePoint 2010 Ribbon
• Screen Cast: Starting with the SharePoint 2010 Ribbon
• More Ribbon locations to extend your SharePoint 2010 UI
• Creating a FlyoutAnchor in the Ribbon
• Adding/Remvoing Social Tagging in the Ribbon
• Building a more complex SharePoint 2010 Ribbon Structure

Go check it out!

In Microsoft SharePoint Foundation, application pages can now inherit a customized site master page through the DynamicMasterPageFile attribute.

In addition, there are a few pages which have been designated as Safeguarded Application Pages. These are the application pages that have safeguards against a broken master page. If these pages encounter an error when loading the dynamic master page, a safe master page in the _layouts folder is loaded instead.

• AccessDenied.aspx
• MngSiteAdmin.aspx
• People.aspx
• RecycleBin.aspx
• ReGhost.aspx
• ReqAcc.aspx
• Settings.aspx
• UserDisp.aspx
• ViewLsts.aspx

Check out the documentation on MSDN regarding master pages in SharePoint 2010.