The cached memory is shown distinctly with a different color, that's fine. The problem is the hover message shows the total included cached memory and there's no setting otherwise. So, it looks like more memory is used than really is.

Reproducible: Always

Steps to Reproduce:
1. Add the system load widget to a panel
2. Hover over it
3. See the memory number be much higher than expected

Actual Results:  
Cached memory is included in total

Expected Results:  
Only actual application and system memory should be included in this number, which is how it is in the System Monitor application.