Hi Amir,
Thank you for contacting Syncfusion support.
In our ButtonAdv control, at present we don’t have default support to achieve it as Cancel button and Default button. We have prepared a workaround sample in which we have invoked the Click event of specific button on the “PreviewKeyDown” event of window. Also, we have inherited the style of ButtonAdv in “App.xaml” and applied Border color for the Button to get selected at the time of loading. Please refer the below sample
Regards,
Keerthana J