Problem
Sometimes it’s hard to see what is going on in the browser window. With the highlight elements plugin we can make things visible.
Prerequisites
The highlight elements plugin can be downloaded from the Firefox add-on manager, using the following url: https://addons.mozilla.org/.
Solution
There is an extra button visible in the toolbar of Selenium IDE after installing the plugin. We can see the button in the following screenshot: 
We can highlight every element which we use in tests by enabling this button.