Wt

In JavaScript, there are the showToolTip()/hideToolTip() function, in ToolTip.js. This needs to be callable from the code.
That way developers are able to control when information can be shown or hidden from the code.

We should also consider what does functionally implies. If we force it to show, so we still want it to show up on hover? Do we still want it to go away after a while?
I believe this merits a setToolTipOptions(Wt::WFlags<ToolTipOption> options) that will control the different possibilities.
The functionality as it is now, showing it on hover, and it disappearing after a while will remain the default.

Mind that this is only likely to work on non-native tooltips. When using native (setting title="..."), it is managed by the browser, and a cursory Google search doesn't lead me to believe this can be accessed from JS.