Dimmer widget on/off button also sending value

[mjaanes]

It is, you can unlimnk on/off object and then it will work only via byte object.

Thanks for the quick answer. 

This is not a very user friendly solution. As with any DALI ECG, you typically want to switch on/off while retaining the same brightness. Using the VALUE byte would mean that one would have to fine-tune the scale every time the light is switched off/on (if I understand your solution correctly).

Must be a bug in the TOUCH 3. I can not think of any good reason why the middle switch on/off button should send the VALUE byte. 
(any standard KNX sensor, e.g. Multitouch with a rotary dimmer or even sensors with physical buttons would never do this).