Unfortunately, MUI Royale currently does not support all of MUI's drag'n'drop functionality. It is, however, possible to use drag'n'drop operations that come from Workbench in the form of app messages.
If your window should be able to accept these messages, you first have to set the
Window.AppWindow attribute to True. After that you have to define
which of your MUI gadgets should accept dropped files. This is done by setting
up a notification on the Notify.AppMessage attribute for the desired gadgets.
As Notify class is the super-class for all MUI gadgets, you can use this
attribute with every MUI object that has a visual representation in form of a gadget.
If you do not want to have specific gadgets as drop targets, you can also setup your
whole window as a drop target by simply setting up a notification on the Notify.AppMessage
attribute for your whole window.
Whenever the user drops an icon over your window or MUI gadget then, you will
get a notification of type AppMessage. See Notify.AppMessage for details.
When your application is iconified and the user drops files on your app icon you can use the attribute Application.DropObject to define the MUI object which should receive the dropped file(s).