TIWCGJQCustomButton.Default Property
If Enabled, the button's OnClick event handler executes when the you press the ENTER key. Although an application can have more than one Default button, the form calls the OnClick event handler only for the first visible and enabled button in internal list. Moreover, any button that has focus becomes the Default button temporarily; hence, if you select another button before pressing ENTER, the selected button's OnClick event handler executes instead.
public property Default: TIWCGJQDefaultButtonOptions read GetDefault write SetDefault;