The Yoix^® Scripting Language

The type that is assigned to the event argument in the declaration of dropActionChanged selects the events that dropActionChanged receives. If event is declared to be a DropTargetEvent then DragSourceEvents will not arrive, if it is declared to be a DragSourceEvent then DropTargetEvents will not arrive, but if event is an Object then DropTargetEvents and DragSourceEvents can arrive and dropActionChanged should check event, usually using instanceof, to decide what to do.

dropActionChanged receives DropTargetEvents when its declaration lets them through and the drop action changes while the cursor is over the component. dropActionChanged usually examines fields, like action in its event argument and then returns a Number that is non-zero if it accepts and zero if it rejects the data that is being transferred by the drag and drop operation. A return value that is missing or the wrong type (e.g., a String) is ignored and no changes are made, which is a little different than dragEnter's behavior.

dropActionChanged receives DragSourceEvents when its declaration lets them through and the drop action changes while this component's dragGestureRecognized is the one that exported the data to the drag and drop operation. dropActionChanged usually examines fields, like action in its event argument and may choose to change the cursor field in its event argument if a visual effect is called for, but in this case nothing special is required and any return value from dropActionChanged will be ignored.

Some Swing components provide automatic drag and drop handling that currently must be disabled by storing NULL in their transferhandler field before your drag and drop event handlers will start working. In other words, you probably should include a declaration that looks something like,

Object transferhandler = NULL;