EGO-L-002 warning

objects created by extension should be destroyed in disable()

Objects assigned in `enable()` are missing matching `.destroy()` calls in `disable()` or its helper methods.

Destroy all objects

• extension.js:64

          this._frameOverlay = new St.Widget({
              style: `border-radius: ${radius}px;` +
                     'background-color: rgba(0,0,0,0.18);' +
                     'border: 2px solid rgba(0,0,0,0.42);',
          })

• extension.js:59

  this._imageActor = new Clutter.Actor({ width, height })