...in the temporary container DIV (and it appears at the end of the page, as the container DIV is appended to dojo.body() - I was planning to remove it later).

What doesn't seem to work is using the innerHTML from the container DIV as the string passed to dijit.showTooltip(). Is there any better way to insert the chart into a tooltip shown by dijit.showTooltip() ?

I have to use dijit.showTooltip() because I want the tooltip to be shown while hovering on a DataGrid cell: the code partially shown in my previous post is executed inside an event handler, and "node" is actually e.cellNode, where e is the event:

dojo.connect(myDataGrid, "onCellMouseOver" , function(e) {
       [...]
       dijit.showTooltip(contdiv.innerHTML, e.cellNode);
    }

dijit.Tooltip has no show() method: this is a method of the object dijit._masterTT, and takes as arguments, among other things, an innerHTML (see source of Tooltip.js). So, I might as well call dijit.showTooltip(), which internally calls dijit._masterTT.show(), and then mess with dijit._masterTT.domNode , replacing its content. But from my limited understanding, altering dijit._masterTT.domNode is a BAD_THING, because the current Tooltip machinery relies on simple replacements of the innerHTML of one of its children, dijit._masterTT.containerNode , so if I damage the DOM structure no other tooltips can be shown. And at http://www.dojoforum.com/node/14857 Dante says that "appendChild()'ing anyWidget.domNode is questionable, and should be used with caution".

Instead, this appears to work, more or less:

1. create a DIV for the chart, insert in the DOM with dojo.body().appendChild() and build the sparkline inside it.
2. show a tooltip (dijit.showTooltip() works fine), and then append the chart's DIV to dijit._masterTT.containerNode :

msg = 'some HTML fragment';
dijit.showTooltip(msg, e.cellNode);
dijit._masterTT.containerNode.appendChild(chdiv);

This has the effect of showing the chart with the sparkline below the msg. Other tooltips keep working normally. However, this solution is not very clean because dijit._masterTT is supposed to be a private object; besides, I'm not sure if the DOM elements of the sparkline chart are properly destroyed once the tooltip is hidden.

What I don't understand is why the chart's HTML code can't just be copied into the tooltip, e.g. with:

msg = 'some HTML fragment';
dijit.showTooltip(msg, e.cellNode);
// dijit._masterTT.containerNode.appendChild(chdiv);
var contdiv = document.createElement('div');
dojo.body().appendChild(contdiv);
contdiv.appendChild(chdiv);
dijit._masterTT.containerNode.innerHTML = contdiv.innerHTML;

This results in an empty tooltip. Isn't HTML with SVG tags like any other HTML content?