friend wxConstraintOp operator % (const int perCent, const wxConstraintOp& arg2);
friend wxConstraintOp operator + (wxConstraintOp& arg1, int margin);
friend wxConstraintOp operator - (wxConstraintOp& arg1, int margin);
friend wxConstraintOp operator % (const int perCent, const wxConstraintOp& arg2);
friend wxConstraintOp operator + (wxConstraintOp& arg1, int margin);
friend wxConstraintOp operator - (wxConstraintOp& arg1, int margin);