CapeWindowId must be an input argument

[kyle]

A CapeWindowId? may contain strings such as display strings. For an input argument this can be handled with a struct that contains constant character pointers.

For an output argument we would need an interface to manipulate the string, much like an ICapeString.

A struct containing an ICapeString pointer could still handle this situation but the M&T SIG does not foresee a situation in which a window handle becomes an output argument.

It is suggested that CapeWindowID arguments must always be input arguments.