I needed to convert a couple of CHAR and NCHAR columns to their VARCHAR/NVARCHAR equivalent, and noticed a peculiar behavior of the SSMS (2008 R2) table designer:
For example, when the original column was defined as CHAR(10), and I added the characters VAR at the beginning of the Data Type field and tabbed to the next column, the editor would not keep the resulting VARCHAR(10), but change the data type to VARCHAR(50), as is the default length for VARCHAR and NVARCHAR columns in the designer.
I found that this behavior was discussed in this SO question as occurring in SSMS 2005, confirmed in 2008, and, by personal experience, still exists in 2008R2 and 2012.
It seems that MS either does not care, or that it does not want to fix weird bugs due to “compatibility issues”.