Why you can't make custom progress monitors in eclipse

I wanted to make a custom progress monitor with a temperature graph in Eclipse, but it does not seem to be possible. Here's why:

There is a ProgressProvider class that has an abstract createMonitor(Job job) method that is called in the JobManager when creating jobs. The standard concrete implementing class is the ProgressManager, shown above in a dashed box labelled "Discouraged Access". So you can't just override this class.

The JobMonitor is an inner class of ProgressManager, and it is not possible to provide an alternative. Once it has been created and passed to the Job, it has already been displayed as a Dialog, so it can't be wrapped with another Dialog.

Seems impossible, really.