Button anomaly?

[Graham Samuel]

I have a stack showing a lot of buttons. These are of type 'standard' and they have rounded corners and a kind of graduated grey fill, without my setting any special properties for them individually. However I have a button in the same stack with nominally the same properties that doesn't have rounded corners. If I change its style to 'roundRect' I lose the grey fill.

Of course I can just start again, creating a new button from scratch and transferring the script of the original button - but can anyone say how this came about? I can't see any special settings of any properties of any of the buttons in the stack.

TIA 

Graham