It's not possible to use fadeToColor() on the 2 leds at the same time about blink4java

[avernois]

Well this a vicious problem :)
Theoritycally, when executing a command, BlinkDevice should claim the usb interface, execute the command and release the claim.
But, if the claim is forced (because the kernel claimed it before), the release implementation is quite extrem and the following claim will reset the device (which cause both led to light off and on again).
This is not nice.

So I don't do the release. Well, it is not clean but as almost all usb client do a forceClaim that's not really a problem.
But, you can't forceClaim the same device twice, wich is the current problem.

So we should ensure that we don't do the claim twice.

(note that this "claim phase" is not part of the usb specification but something added by OS kernel)

[ludopradel]

It works, thanks !