play around with faders, WIP

src/ui/ui_icons.h

@@ -8,6 +8,8 @@ enum UI_IconID {
     UI_ICON_CHECK,
     UI_ICON_CHEVRON_DOWN,
     UI_ICON_KNOB,
+    UI_ICON_SLIDER_THUMB,
+    UI_ICON_FADER,
     UI_ICON_COUNT
 };