Files dropped in the image may be never released

[LinqLover]

Because probably no one knows who should be responsible for closing the relevant streams.

Drop files events are the only type of the that MUST be handled to avoid keeping the streams open. As an advocate of the #readOnlyFileNamed:do: pattern (i.e., executeAroundMethod is responsible for closing), I wish we could do something similar close to HandMorph>>#generateDropFilesEvent:. Maybe this method should only check for the drop file names and handlers (such as the world) should be responsible for opening and closing the files.