Double click in Add soundfont/sfz list should equal Load command

1. View > Synthesizer > Fluid
2. Add button
3. Double click an item in the list

Expected action: The item is added/loaded into the synth list in correspondence with expected file open dialogs behavior when double clicking an item in the list
Actual action: The item is just selected (as when single clicking it) and you still have to manually press the Load button

The Zerberus SFZ list selection is lacking the same expected behavior.