where can I declare a global variable

[Danielle Harvey]

I want to declare a global variable, one that all classes that I
ever create in a single program will have as a declared variable.
Unfortunately if I declare 'int g_var;' at the top of the view
or doc class, other classes that I create don't recognize it
even if I put the #include <view> at the top of the class.

The question is, how can I declare a global variable?