message: fix(stream-client):show only add-stage button (without tiles-separator) in stream-diagram component.
diff: padding: 8px;
  margin-top: 24px;
  width: 100%;
  + z-index: 0;
  &:hover {
  background-color:rgba(255, 255, 255, 0.3);
  -
  - }
  - &:hover{
  .visible-on-hover{
  opacity: 1;
  }
  -
  + .add-button:before {
  + opacity: 0.5;
  + }
  }
  }
  @@ -44,14 +44,19 @@ flogo-diagram {
  height: 8px;
  top: 44%;
  left: -2px;
  + z-index: -1;
  + }
  }
  - &.add-button{
  +.add-button{
  margin: 0 4px 0 48px;
  min-width: 44px;
  &:before {
  width: 52px;
  left: -48px;
  + opacity: 0;
  }
  + &.visible-on-hover:before {
  + opacity: 0.5;
  }
  }
  .tile-placeholders{
  