I have created a new Component (a TDBRTFEditor). Now this Component have a property mageList. The main problem was that I have to set the ItemIndex value by myself.
When creating the Action at Designtime from Standard Actions this data and all other properties are copied from a existing Version of the (Standard) Action (it was hard to figure out how this works while the documentation is poor about Standard Actions).
Unfortunately I can't use Standard Action in my Component. I received some errors when the Component is created (design time as well as run time). I stopped this way and using the property ImageList in my Component.