Though it is still possible (at the time of writing this book) to develop with the CSIDE Development Environment. To open the Development Environment, you have to install Microsoft Dynamics NAV Development Environment (or Microsoft Dynamics 365 Business Central Development Environment, the appearance and the name are similar). Open it and navigate to Tools | Object Designer (or press Shift + F12). The following window will open:
On the left-hand side, you will find a number of icons representing the different objects available. On the right-hand side, you will see a list of all the existing objects ...