Patch Set 1: I would prefer that you didn't submit this

This change works for java files. In case of eg. xml files d-n-d will insert file name or path into xml file content.

Here are steps to reproduce this:
1. Open an xml file eg. pom.xml by dragging from repositories view or from package explorer
2. Grab a file from repositories view and drop it on xml editor
3. bum, you inserted path to dropped file into xml content