Quote Originally Posted by SilverWarior View Post
According to official documentation about Steam Overlay that you can find here https://partner.steamgames.com/doc/features/overlay DirectX 7 is supported. The documentation also states that you need to initialize Steam API before your game render surface is created in order for the API to successfully hook the rendering device creation.
Another cause for your problem might be the fact that UnDelphiX might be actually running in software mode with which Steam Overlay is not compatible.
Thanks, I am starting Steam first, but I'm unable to get it to work. I'm actually wondering if UnDelphiX really uses DirectX 7 for 2D, I don't think DirectDraw was ever changed after DirectX 5. I set doDirectX7 and do3D and from looking at the source it does seem to load a DX7 object at some point, but Steam never hooks to it, strange.

Anyway, I made a new rendering engine using OpenGL and set that as default and now the Steam overlay works fine.