This attribute is a boolean value which controls how keys are
used. If KeyCase is zero, then key strings supplied to any method
are automatically converted to upper case before being used. If
KeyCase is non-zero (the default), then supplied key strings are
used without modification.
The value of this attribute can only be changed if the KeyMapKeyMap is
empty. Its value can be set conveniently when creating the KeyMap.
An error will be reported if an attempt is made to change the
attribute value when the KeyMap contains any entries.