You’re probably missing the * in front of the declaration of Button.
operator == exist for any pointer to any pointer of the same type.
Typically:
if (&imageButton == buttonClicked) // Good if imageButton declared as ImageButton imageButton
if (imageButton == buttonClicked) // Good if imageButton declared as ImageButton * imageButton
You asked this question both in the #JUCE IRC channel and on StackOverflow and I answered you in both places. Why is it necessary to continually re-ask the question?