fix widget list re-fetch post support synth

src/kiri/function.js

@@ -52,9 +52,11 @@ function prepareSlices(callback, scale = 1, offset = 0) {
     view.set_slice();
     conf.save();
 
+    // allow client.js to generate support widgets
     event.emit('slice.begin', settings.mode);
 
-    const slicing = widgets
+    // refresh widget list because slice.begin may generate supports
+    const slicing = api.widgets.all()
         .slice()
         .filter(w => !w.track.ignore && !w.meta.disabled);
     const totalv = slicing.map(w => w.getVertices().count).reduce((a,v) => a + v);