Strangest error ... like really strange :)

[wysota]

The probable reason is that:

Control control;

Control control;

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This is a declaration of an object "control" of class "Control".

Contol control();

Contol control();

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This is a declaration of function called "control" returning an instance of class "Control".

Of course withouth calling show() you won't see anything regardless if you use "Control control;" or "Control control();".