BOOL anyDevices = !![self.delegate numberOfDevicesInDeviceList:self];
[self.inputsTree beginUpdates];
[self.inputsTree removeItemsAtIndexes:[[NSIndexSet alloc] initWithIndex:idx]
inParent:nil
BOOL anyDevices = !![self.delegate numberOfDevicesInDeviceList:self];
[self.inputsTree beginUpdates];
[self.inputsTree removeItemsAtIndexes:[[NSIndexSet alloc] initWithIndex:idx]
inParent:nil