How to restore 'Remove unused usings' context action?

Hello.

I'm user of #D 5.0 release.

Inside a using block there is a context actions menu with two options:

1. Remove unused usings
2. Sort usings

Also this menu has little arrow button, which activates checkboxes for menu options. If I uncheck it, then aproppriate option hides from the context action menu.

Sort usings option can be restored from Context actions panel (Tools - Options - Coding - C# - Context actions), but setting for Remove unused usings is absent! So I don't understand how I can to restore a visibility for this option.

Also I tried to reinstall SharpDevelop but without results!