Unable to prepend namespace to a class name in C++ class wizard

The "Class name" field on the Define Class pane of  the C++ Class creation wizard does not accept colons ":" in the middle of already entered text. This makes it cumbersome to add a namespace to a class if I forgot to do it right away.

E.g. given "MyClass" already entered in the Class Name field, an attempt to place it into "foo" namespace results in

foo|MyClass

where vertical bar shows the cursor position. At this point attempts to enter "::" do nothing.

The workaround is to cut the rest of the name into clipboard, type "::", then paste the name back.