This is pretty easy to handle actually. Start by adding a test step "Verify element exists" where src=plus.gif. Now use this Verify step as the condition of a logical IF/ELSE block. When you run the test if Test Studio can find src=plus.gif it will execute he IF block which should have the steps to click the Plus symbol thus expanding the item. Otherwise the ELSE block will execute which can be empty, i.e. do nothing.