I've seen WPF demos where the property of a control is bound to the value of another control. For example there could be a textblock where its content's fontsize is controlled by a slider on the same form. Move the slider left and the textblock's content shrinks. Move the slider right and the text grows larger. Pretty straight forward and cool since no code is involved short of the actual XAML.

I came a video that showed how a button's enabled state was conditional depending of if a textbox had any value. If it had any text, the button was enabled. If the textbox was empty the button was disabled. The thing that surprised me was the fact that the button's state was being set in code!! It was not bound to the textbox. Is there no way to do what I've described without code (and using binding)?

TIA
Mike