When the mouse hovers a graphical object in the ajax client, a request is made to the QlikView server to ask for the tooltip to display at the mouse location, allowing the tooltip text to be computed only when needed. Is there a way to implement the same behavior in an extension object? I thought about adding an expression to my extension object to hold the tooltips of every row but it seems to be a waste of computing time and bandwidth since most of the tooltips will never be display, so I am looking for a cleaner solution.