[Pharo-users] ifCurtailed prompts debug window

Hello, On Windows 10 and Pharo 8, If I do: [ Error signal ] ifCurtailed: [ Transcript show: 'error' ]. the debug window pops up, when I close, 'error' is print in the Transcript. If I do [ Error signal ] on: Error do: [ Transcript show: 'error' ]. 'error' is print in Transcript without debug windows pops up. I was expecting the same behavior here, as if ifCurtailed was a syntax sugar for on:do:, that is not the case or it is some kind of error? The way it is, I cannot use ifCurtailed because I don't want the debug window to pup up. Regards, Vitor