🎉 Allow setting actor transitions in overview

docs/how-to-create-new-effects.md

@@ -121,7 +121,8 @@ var SimpleFade = class SimpleFade {
 
   // This will be called in various places where a unique identifier for this effect is
   // required. It should match the prefix of the settings keys which store whether the
-  // effect is enabled currently (e.g. the '*-close-effect').
+  // effect is enabled currently (e.g. '*-close-effect'), and its animation time
+  // (e.g. '*-animation-time').
   static getNick() {
     return 'simple-fade';
   }
@@ -148,24 +149,12 @@ var SimpleFade = class SimpleFade {
     return new Shader(settings);
   }
 
-  // This is also called from extension.js. It is used to tweak the ongoing transitions of
+  // This is also called from extension.js. It is used to tweak the ongoing transition of
   // the actor - usually windows are faded to transparency and scaled down slightly by
-  // GNOME Shell. Here, we modify this behavior as well as the transition duration.
-  static tweakTransitions(actor, settings) {
-    const animationTime = settings.get_int('simple-fade-animation-time');
-
-    const tweakTransition = (property, value) => {
-      const transition = actor.get_transition(property);
-      if (transition) {
-        transition.set_to(value);
-        transition.set_duration(animationTime);
-      }
-    };
-
-    // We re-target these transitions so that the window is neither scaled nor faded.
-    tweakTransition('opacity', 255);
-    tweakTransition('scale-x', 1);
-    tweakTransition('scale-y', 1);
+  // GNOME Shell. For each property, you can set a "from", "to", and a "mode". For this
+  // effect, windows should neither be scaled nor faded.
+  static getCloseTransition(actor, settings) {
+    return {'opacity': {to: 255}, 'scale-x': {to: 1.0}, 'scale-y': {to: 1.0}};
   }
 }