@ustk @d-healey Ok it's working, thanks for your help !
Solved with this code :

//Combo box
const var cmbSampleMap = Content.getComponent("cmbSampleMap");
cmbSampleMap.set("items", sampleMaps.join("\n"));


inline function oncmbSampleMapControl(component, value)
{
	Sampler1.asSampler().loadSampleMap(sampleMaps[value-1]);
	for (i = 0; i < 127; i++)

 if (Sampler1.asSampler().isNoteNumberMapped(i))
    Engine.setKeyColour(i, Colours.withAlpha(Colours.blue, 0.3));
    else
   Engine.setKeyColour(i, Colours.withAlpha(Colours.white, 0.0));

};

Feature Request : A Drum Step Sequencer like arpeggiator module with associate sliderpack component :

Basic things :

Pattern length
Time grid (1/16, 1/32 etc.)
Magnetism on grid or free
12 or 16 tracks / sample slot
MIDI rec input from the keyboard or the drum pad
Syncronized BPM with Daw or free

For more, Hise's user can customize it :

Colors, background
Volume, pan, pitch on each sample slot
Drag user sample
Repeated note
Drum machine groove
send CV / Gate
FX send
and I must forget ...

Drums sequencer in Hise ?

@ustk Of course, it's beter to learn and do something personalized, but step sequencers often have the same characteristics, we would save time by having a c...

Forum (forum.hise.audio)

@Christoph-Hart A configurable step sequencer would be a good feature to add in the future update of Hise like the floating tile keyboard.

I thought I had 128 frames but the export started at frame 0 so 'ive 129 frames. Noob error, problem solved. Thanks

@d-healey Great thanks ! It's compiles AU/VST now.
I'm on macOS Mojave 10.14.6, I've downgraded Xcode from 11.3.1 to 10,1, upgraded Projucer to 6.0.5 and use Hise - Scriptnode version.
(I detail my configuration it can help someone else)