Nested comments are quite cool and have been included in BlogEngine.NET for the past few releases, but I never got around to implementing them into my theme. I learned it was quite simple.
Edit CommentView.ascx file and…
add this code line somewhere at the bottom of the display of the comment,
maybe near the <%= AdminLinks %>,
add this bit of code: <%= ReplyToLink %>
This will add a Reply link to the bottom of each comment.
And just before the end of the file, add the following line of code before the last close div tag.
<div class="comment-replies" id="replies_<%=Comment.Id %>"
<%= (Comment.Comments.Count == 0) ? " style=\"display:none;\"" : "" %>>
<asp:PlaceHolder ID="phSubComments" runat="server" />
</div>
This will display the comment form right under the reply link when you click on the reply link.
Next, edit the theme style sheet and the following style class.
.comment-replies {
background: transparent url(../../pics/reply-arrow.gif) no-repeat 2px 2px;
padding: 0 0 0 15px;
margin: 5px 0 0 0;
}
This will indent the reply comment with a little arrow.
Sample:

Tags: blogengine.net, theme