EMPTYING THE WEBPROG3 SITE CACHE
In the Firefox menu, select "Settings" and then "Privacy & Security".
From there, scroll down to find "Manage browsing data".
Type in "webprog3" and select the site name below.
Then click on "Remove Selected" and "Save Changes".

Close the settings tab.
EMPTYING THE WEBPROG3 SITE CACHE
To make sure you are working with the latest facilities of webProg3 and that bugfixes etc. are correctly applied, it is a good idea to empty the site cache on a regular basis. If you do not do this, the Firefox browser will use historical data stored in its cache instead. This will not always be appropriate, and it can even stop webProg3 working as it should.

It is very quick and simple to do. See instructions below.
Navigate to the webprog3 website if you are not there already, and refresh your browser. Run the Main Editor.