Is it possible to add literal XML data within a C# code file? I'm currently using a multiline string literal but it gets messy as you can see. Any better way of doing this?
string XML = @"<?xml version=""1.0"" encoding=""utf-8""?>
<customUI xmlns=""http://schemas.example.com/customui"">
<toolbar id=""save"">
</toolbar>
</customUI>";
XML literals are a feature of VB.NET, not C#.
What you have posted is as close as you can get in C#.
You may want to consider replacing the embedded double quotes with single quotes though (as both types are valid XML).
For larger amounts of XML you may want to consider the answer from Marc - using an XML file (loaded once and stored in memory), so you can take advantage of the XML editor.