I having a issue with a proyect created on the IDE that works ok, but when I try to run in on another app with a IDEScripter component only(No Engine Component) I get "Class Button not Found" Empty form works ok. I have included "ap_Buttons.pas" on the project with no success.
Regarding your question, the IDE registers the components to be used in the palette, calling RegisterComponent, and such function calls RegisterClass in turn: