diff --git a/apps/setuichange/boot.js b/apps/setuichange/boot.js
new file mode 100644
index 000000000..3a30c43a9
--- /dev/null
+++ b/apps/setuichange/boot.js
@@ -0,0 +1,153 @@
+(function(mode, cb) {
+  var options = {};
+  if ("object"==typeof mode) {
+    options = mode;
+    mode = options.mode;
+    if (!mode) throw new Error("Missing mode in setUI({...})");
+  }
+  var redraw = true;
+  if (global.WIDGETS && WIDGETS.back) {
+    redraw = false;
+    WIDGETS.back.remove(mode && options.back);
+  }
+  if (Bangle.btnWatches) {
+    Bangle.btnWatches.forEach(clearWatch);
+    delete Bangle.btnWatches;
+  }
+  if (Bangle.swipeHandler) {
+    Bangle.removeListener("swipe", Bangle.swipeHandler);
+    delete Bangle.swipeHandler;
+  }
+  if (Bangle.dragHandler) {
+    Bangle.removeListener("drag", Bangle.dragHandler);
+    delete Bangle.dragHandler;
+  }
+  if (Bangle.touchHandler) {
+    Bangle.removeListener("touch", Bangle.touchHandler);
+    delete Bangle.touchHandler;
+  }
+  delete Bangle.uiRedraw;
+  delete Bangle.CLOCK;
+  if (Bangle.uiRemove) {
+    let r = Bangle.uiRemove;
+    delete Bangle.uiRemove; // stop recursion if setUI is called inside uiRemove
+    r();
+  }
+  g.reset();// reset graphics state, just in case
+  if (!mode) return;
+  function b() {
+    try{Bangle.buzz(30);}catch(e){}
+  }
+  if (mode=="updown") {
+    var dy = 0;
+    Bangle.dragHandler = e=>{
+      dy += e.dy;
+      if (!e.b) dy=0;
+      while (Math.abs(dy)>32) {
+        if (dy>0) { dy-=32; cb(1) }
+        else { dy+=32; cb(-1) }
+        Bangle.buzz(20);
+      }
+    };
+    Bangle.on('drag',Bangle.dragHandler);
+    Bangle.touchHandler = d => {b();cb();};
+    Bangle.btnWatches = [
+      setWatch(function() { b();cb(); }, BTN1, {repeat:1, edge:"falling"}),
+    ];
+  } else if (mode=="leftright") {
+    var dx = 0;
+    Bangle.dragHandler = e=>{
+      dx += e.dx;
+      if (!e.b) dx=0;
+      while (Math.abs(dx)>32) {
+        if (dx>0) { dx-=32; cb(1) }
+        else { dx+=32; cb(-1) }
+        Bangle.buzz(20);
+      }
+    };
+    Bangle.on('drag',Bangle.dragHandler);
+    Bangle.touchHandler = d => {b();cb();};
+    Bangle.btnWatches = [
+      setWatch(function() { b();cb(); }, BTN1, {repeat:1, edge:"falling"}),
+    ];
+  } else if (mode=="clock") {
+    Bangle.CLOCK=1;
+    Bangle.btnWatches = [
+      setWatch(Bangle.showLauncher, BTN1, {repeat:1,edge:"falling"})
+    ];
+  } else if (mode=="clockupdown") {
+    Bangle.CLOCK=1;
+    Bangle.touchHandler = (d,e) => {
+      if (e.x < 120) return;
+      b();cb((e.y > 88) ? 1 : -1);
+    };
+    Bangle.btnWatches = [
+      setWatch(Bangle.showLauncher, BTN1, {repeat:1,edge:"falling"})
+    ];
+  } else if (mode=="custom") {
+    if (options.clock) Bangle.CLOCK=1;
+    if (options.touch)
+      Bangle.touchHandler = options.touch;
+    if (options.drag) {
+      Bangle.dragHandler = options.drag;
+      Bangle.on("drag", Bangle.dragHandler);
+    }
+    if (options.swipe) {
+      Bangle.swipeHandler = options.swipe;
+      Bangle.on("swipe", Bangle.swipeHandler);
+    }
+    if (options.btn) {
+      Bangle.btnWatches = [
+        setWatch(function() { options.btn(1); }, BTN1, {repeat:1,edge:"falling"})
+      ];
+    } else if (options.clock) {
+      Bangle.btnWatches = [
+        setWatch(Bangle.showLauncher, BTN1, {repeat:1,edge:"falling"})
+      ];
+    }
+  } else
+    throw new Error("Unknown UI mode "+E.toJS(mode));
+  if (options.remove) // handler for removing the UI (intervals/etc)
+    Bangle.uiRemove = options.remove;
+  if (options.redraw) // handler for redrawing the UI
+    Bangle.uiRedraw = options.redraw;
+  if (options.back) {
+    var touchHandler = (_,e) => {
+      if (e.y<36 && e.x<48) {
+        e.handled = true;
+        E.stopEventPropagation();
+        options.back();
+      }
+    };
+    Bangle.on("touch", touchHandler);
+    // If a touch handler was needed for setUI, add it - but ignore touches if they've already gone to the 'back' handler
+    if (Bangle.touchHandler) {
+      var uiTouchHandler = Bangle.touchHandler;
+      Bangle.touchHandler = (_,e) => {
+        if (!e.handled) uiTouchHandler(_,e);
+      };
+      Bangle.on("touch", Bangle.touchHandler);
+    }
+    var btnWatch;
+    if (Bangle.btnWatches===undefined) // only add back button handler if there's no existing watch on BTN1
+    btnWatch = setWatch(function() {
+      btnWatch = undefined;
+      options.back();
+    }, BTN1, {edge:"falling"});
+    WIDGETS = Object.assign({back:{
+      area:"tl", width:24,
+      draw:e=>g.reset().setColor("#f00").drawImage(atob("GBiBAAAYAAH/gAf/4A//8B//+D///D///H/P/n+H/n8P/n4f/vwAP/wAP34f/n8P/n+H/n/P/j///D///B//+A//8Af/4AH/gAAYAA=="),e.x,e.y),
+      remove:(noclear)=>{
+        if (btnWatch) clearWatch(btnWatch);
+        Bangle.removeListener("touch", touchHandler);
+        if (!noclear) g.reset().clearRect({x:WIDGETS.back.x, y:WIDGETS.back.y, w:24,h:24});
+        delete WIDGETS.back;
+        if (!noclear) Bangle.drawWidgets();
+      }
+    }},global.WIDGETS);
+    if (redraw) Bangle.drawWidgets();
+  } else { // If a touch handler was needed for setUI, add it
+    if (Bangle.touchHandler)
+      Bangle.on("touch", Bangle.touchHandler);
+  }
+})