To achieve this you can use Bootstrap Tooltip widget from app store instead of configuring tooltip on link button. By default tooltip on link button is visible only on hover and not on focus but using this widget you can configure it based on your requirements.
Hope this helps!
AFAIK, Tooltip is available only on hovering. The logic of displaying the tooltip may be inbuilt on the button widget provided by Mendix. Can you elaborate on your use case a bit?
The use case is the following: I have a page with a Link button. This link button does not have any on click events. It only has a tooltip that shows a description of a graph in this same page. Now if the user clicks on this button the tooltip disappears. I want to stop this behavior.