Yes they are the same .Net user control. It is called UserInfo and it is called like this in pages.
<ui:UserInfoBar id="UserNotification" runat="server" />
or if called from a different editor than CME
<ui:UserInfoBar id="UserNotification" runat="server" SourceEditor="CME" />
The related items area is not extendable out of the box, but if you do some hack and add an extendable area then you can extend things there. For instance this is the markup by default.
<div id="ActivityRelatedListButtonWrapper">
<c:Button id="BtnPreview" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Preview %>" Title="<%$ Resources: Tridion.Web.UI.Strings, Preview %>" />
<c:Button id="BtnCompare" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Compare %>" Title="<%$ Resources: Tridion.Web.UI.Strings, Compare %>" />
<c:Button id="OpenActivityRelatedItem" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Open %>" />
</div>
You can add an extendable area like this.
<div id="ActivityRelatedListButtonWrapper">
<c:ExtendableArea id="Pre_ExtendableArea" runat="server" />
<c:Button id="BtnPreview" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Preview %>" Title="<%$ Resources: Tridion.Web.UI.Strings, Preview %>" />
<c:Button id="BtnCompare" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Compare %>" Title="<%$ Resources: Tridion.Web.UI.Strings, Compare %>" />
<c:Button id="OpenActivityRelatedItem" disabled="disabled" runat="server" Label="<%$ Resources: Tridion.Web.UI.Strings, Open %>" />
<c:ExtendableArea id="Post_ExtendableArea" runat="server" />
</div>
These extendable areas can be used to inject a .Net User Control.
Tridion 2013 Workflow gives you a Object Oriented
capabilities that can be used to define external activities specialized on Email Dispatching
similar of what you have with YAWF. However if you really need a Handlers
behavior like YAWF you can do it by extending the Script Executor as I describe in this post Extending Workflow Scripts