Question

In the Visual Studio 2010 SDK there is SnapshotSpans and VirtualSnapshotSpans. According to MSDN, the difference is the Virtual Span has Virtual Spaces, the other does not.

What exactly is a Virtual Space?

For reference:
http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.text.virtualsnapshotspan.aspx

Answer 1

You can find an explanation here:

http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.text.virtualsnapshotpoint%28v=vs.100%29.aspx

Virtual spaces are “extra” spaces at the end of a line that do not add
to the length of the line. You can enable or disable virtual spaces in
Visual Studio. When virtual spaces are disabled, pressing on the right
arrow key at the end of a line causes the caret to move to the
beginning of the next line. When virtual spaces are enabled, pressing
on the right arrow key at the end of a line causes the caret to move
forward on the same line.

Even if the option “Enable virtual Space” under Tools -> Options -> Text Editor -> All Languages -> General is disabled, virtual spaces can be inserted when writing indented text or code.

If you type enter at the end of an indented line, Visual Studio adds virtual spaces at the beginning of the new line. These spaces are “virtual” since they have not been typed by the user and will not be saved in the file unless you enter something after the virtual spaces.

This affects the position of the caret:
After pressing enter at the end of an indented line the “BufferPosition”- and “VirtualBufferPosition”-properties of CaretPosition will be different.
BufferPosition points to column 0 in the new line and VirtualBufferPosition points to the position where the caret is visually rendered.