voldisp: make sure widgets wont draw over volume bar

apps/voldisp/boot.js

@@ -4,6 +4,44 @@
     if (timeout) {clearTimeout(timeout); timeout=undefined;}
 
     if (Bangle.CLOCK) {
+
+      const WIDGET_UTILS_HIDE = function() {
+        //exports.cleanup();
+        if (!global.WIDGETS) return;
+        g.reset(); // reset colors
+        for (var w of global.WIDGETS) {
+          if (w._draw) return; // already hidden
+          w._draw = w.draw;
+          w.draw = () => {};
+          w._area = w.area;
+          w.area = "";
+          if (w.x!=undefined) g.clearRect(w.x,w.y,w.x+w.width-1,w.y+23);
+        }
+      };
+      /// Show any hidden widgets
+      const WIDGET_UTILS_SHOW = function() {
+        //exports.cleanup();
+        if (!global.WIDGETS) return;
+        for (var w of global.WIDGETS) {
+          if (!w._draw) return; // not hidden
+          w.draw = w._draw;
+          w.area = w._area;
+          delete w._draw;
+          delete w._area;
+          w.draw(w);
+        }
+      };
+
+      let isAllWidgetsHidden = true;
+      if (global.WIDGETS) {
+        for (var w of global.WIDGETS) {
+          if (!w._draw) {
+            isAllWidgetsHidden = false;
+            break;
+          }
+        }
+      }
+      WIDGET_UTILS_HIDE();
       let barWidth = g.getWidth()*volPercent/100;
       g.
         setColor(0x0000).fillRect(0,0,g.getWidth(),24).
@@ -12,17 +50,9 @@
         drawString("volume",barWidth,1);
 
       let goAway = ()=>{
-        let isAllWidgetsHidden = true;
-        if (global.WIDGETS) {
-          for (var w of global.WIDGETS) {
-            if (!w._draw) {
-              isAllWidgetsHidden = false;
-              break;
-            }
-          }
-        }
         if (!isAllWidgetsHidden) {
-          Bangle.drawWidgets();
+          g.reset().clearRect(0,0,g.getWidth(),24);
+          WIDGET_UTILS_SHOW();
         } else if (Bangle.uiRedraw) {
           Bangle.uiRedraw();
         } else {
@@ -33,5 +63,5 @@
     }
   };
   Bangle.on("musicVolume", onMusicVolume);
-  //GB({t:"audio",v:10});
+  //GB({t:"audio",v:66});
 }