Is there any new information about this? As of Lazarus 0.9.30.4 and fpc 2.6.0 w carbon widgetset, this problem is still there.
In researching it, it looks like apps have to call an api function (registerForDraggedTypes) to register the types of files they can accept, otherwise the OS will not even send the appropriate messages to the app when files are dropped.
Then, when files are dropped on the app certain messages need to be responded to, and when I looked at the source code in the place where it deals with kAEOpenDocument, I did not see any mention of the other messages that need to be responded to.
registerForDraggedTypes is a procedure of the NSview class. I'm trying to figure out what that is exactly, but it seems like it is just a rectangle representing a visible area. I'm trying to figure out if I can create an NSview object for my main form window and then call registerForDraggedTypes. But this is my first time at doing any programming on Mac so I really don't know what I'm doing.
If anyone has any new info on getting onDropFiles to fire when dropping files onto the running app itself (not just the dock icon), please let me know.