NB: 200707231200

Popup dialog does not appear when drop an operation from interface A to interface B, and there is already
an existing operation with the same name in interface B.

Steps:
 - Setup:
    1) Create a UML project
    2) Create a class diagram
    3) From the project tree, Right click Model -> New -> Package
    4) Create 2 interfaces int1, int2
    5) Within the interface int1,  create an operation named op1 
    6) Within the interface int2,  create an operation named op1

1) DnD operation op1 from int1 to int2
2) Since the operation name is similar to the one in int2,  there should be a popup
   dialog "Duplicate Element Found" to notify the user.

   Dialog currently appears when performing DnD in the diagram editor
   (See attached dialog)