Add widget visibility library

modules/widget_utils.js

@@ -0,0 +1,28 @@
+/* Utilities for handling widgets - mainly showing/hiding */
+
+/// hide any visible widgets
+exports.hide = function() {
+  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
+exports.show = function() {
+  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);
+  }
+};