Enable firebug in Firefox browser to capture the debug information of Zimbra Webclient.
Refer the following steps to download, install and enable firebug.
Visit Firefox Addon website to download Firebug.
You will get the Install Addon prompt in firefox browser. Click on install button and it will ask for restart of firefox.
After restart, you will get the firebug icon at the right side of address bar.
Firebug landing window
When you clicked on firebug icon, you will get the landing window.
Enable Firebug console
At the first time it will ask to enable the firebug console, click on enable option.
Capture Debug Information
Run the test case and click on "All" and expand every request to capture the debug information.