message: Media item cover directive responds when media item is cleared/changed.
diff: -import { Component, Input, Output, Inject, EventEmitter } from 'ng-metadata/core';
  +import { Component, Input, Output, Inject, EventEmitter, OnChanges, SimpleChanges } from 'ng-metadata/core';
  import * as template from '!html-loader!./cover.html';
  import { Screen } from '../../../../lib/gj-lib-client/components/screen/screen-service';
  @@ -11,7 +11,7 @@ import { Ruler } from '../../../../lib/gj-lib-client/components/ruler/ruler-serv
  transclude: true,
  },
  })
  -export class CoverComponent
  +export class CoverComponent implements OnChanges
  {
  @Input( '<' ) mediaItem: any;
  @Input( '<' ) shouldParallax = false;
  @@ -59,6 +59,13 @@ export class CoverComponent
  } );
  }
  + ngOnChanges( changes: SimpleChanges )
  + {
  + if ( changes['mediaItem'] || changes['maxHeight'] ) {
  + this.setDimensions();
  + }
  + }
  +
  setDimensions()
  {
  if ( this.mediaItem ) {
  