view corrupted when viewed using design feature
Yes, the view designer is a horribly crippled, buggy piece of garbage you shouldn't be using to "design" your views. It should be called the view destroyer, because it can do exactly what you've observed: re-write any non-standard T-SQL into what it thinks you meant. And by "any non-standard T-SQL" I mean anything not predicted by the two developers who likely spent about a day testing this "feature."

Always, always, always modify your views using Script View As > Alter to > New Query Editor Window.

See these related Connect items:

http://connect.microsoft.com/SQLServer/feedback/details/465498/ssms-designer-is-sending-incorrect-alter-statement-to-engine-when-we-have-geomerty-data-type

Where I mention in the workarounds:


  Obviously a better approach is to right-click the view, script as alter to new window. I wonder when they'll admit defeat and ditch the visual designers altogether. They cause more problems than they solve, IMHO.


http://connect.microsoft.com/SQLServer/feedback/details/362679/ssms-right-click-on-a-view-to-edit

Where I do something similar, and

http://connect.microsoft.com/SQLServer/feedback/details/459202/no-edit-option-when-right-clicking-on-a-view-in-management-studio-2008

Where I ask:


  Didn't Edit bring up the horrible graphic designer for views, which was riddled with bugs and lacked support for several basic T-SQL constructs? Isn't that what Design does now?