tls.addButton().click();
checkLabelsCorrectness(tls, new String[]{"item_Label_1", "item_Label_4", "item_Label_6", "item_Label_7"},
new String[]{"item_Label_3", "item_Label_5", "item_Label_2"}, "Available items", "Selected items");
ElementInspector submit = element("formID:submit");
submit.clickAndWait();
tlsOutput.assertText("item_Value_3 item_Value_5 item_Value_2 ");
//add one item by doubleclick
tls.leftList().doubleClick();
checkLabelsCorrectness(tls, new String[]{"item_Label_1", "item_Label_4", "item_Label_6"},