The tooltip should not disappear after few seconds.
The tooltip should hold on as long as the mouse pointer is over the analyzed object.
After hovering, you get the details, but when you want to focus and think about what the numbers mean - boom, they disappear.
I witnessed many times customers getting confused with that and I don't see why the tooltip should have a timeout.
It is especially disturbing on graphs with more data, like scatter plot where you can have four measures (x, y, size, color) and when you want to read into the details in a popup - no chance, it will first disappear.
Alternatively, please inform about the appropriate property in custom themes to be changed to change the timeout.