panel^ form2 = gcnew panel;
form2->ShowDialog();

#include "MyForm.h"

#include "Form1.h"
#include "Form2.h"

error C2061: syntax error : identifier 'panel'
 error C2065: 'form2' : undeclared identifier
 error C2065: 'form2' : undeclared identifier
 error C2065: 'panel' : undeclared identifier
 error C2227: left of '->ShowDialog' must point to class/struct/union/generic type