Search box handles "delete" key incorrectly

Pre:
- OS X 10.8.5
- External keyboard is attached (Standard American)
- iSoul 0.5.0 Beta 1 (0.5.0.b1)

Scenario:
- Click on search field
- Type "foobar", place cursor between "foo" and "bar"
- Press "Delete" key

Expected:
- Letter "b" is deleted, search field contains "fooar"

Actual:
- Text left intact
- Active transfer is removed