I've implemented a solution similar to the one shown here: http://www.telerik.com/DEMOS/ASPNET/Prometheus/ToolTip/Examples/LoadOnDemand/DefaultCS.aspx

A tooltip is shown on demand, and just as in the example, the "trigger" of the tooltip is set programatically. The problem I've found is that sometimes that trigger is close to the page border and when the tooltip is shown, it appear out of the page bounds.

Is there any way to prevent that?

Hello Mark,

This was not considered before, but if you get and use the latest version of RadToolTip "Prometheus" this issue will not occur.

If you continue experiencing problems with this, please, open a new support ticket and send us a simple project which reproduces the problem with the latest RadToolTip's version.

Sincerely yours,
Svetlina
the Telerik team