private int verifyChildren(int pos) {
    return ((HBox) toolbarControl.getChildren().get(pos)).getChildren().size();
  }
Returns the amount of children containing in the specified box.

@param pos 0 for searching the left box, 1 for searching in the right box
@return the amount of children containing in the specified box.
workbenchfx-core/src/test/java/com/dlsc/workbenchfx/view/controls/ToolbarControlTest.java