Deeper debugging tools?

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I have a complex epub3 full of apps that either draw directly to the Canvas or to the Canvas indirectly via a JQuery graphing plugin. The XHTML works perfectly in Chrome, Firefox and iPad Safari. The ebook works perfectly in Azardi (which uses the Firefox engine). In Readium the ones where I draw directly to Canvas work fine.

Here's the subtle bug. In Readium if the graphing happens to appear on the first page of a new section then it works perfectly. But if I put some random and harmless text in front of it so it appears on a second page of that same section, then the graphing canvas is a complete blank - right shape and size, but nothing shows. The calculations associated with the js code work well so it's not that things suddenly stopped working half way through my js.

If I turn on the Chrome debugger I get no errors
(well, recently I get "window.webkitStorageInfo is deprecated. Use navigator.webkitTemporaryStorage or navigator.webkitPersistentStorage instead", but that's a new Chrome bug and is ebook independent).

The question is, are there any tips/tricks for digging deeper via (I assume) the Chrome debugger. How might I look for some cause of a canvas not appearing on the Readium screen?

It seems to be Webkit specific because (a) Azardi works perfeclty and (b) I get nearly the same behaviour in iBooks, though in that case even if the graphic is on the first page of a section it doesn't render. But it's a "Webkit in ebook" error because, as I said, they XHTML works perfectly in Chrome and iPad Safari.

I have, of course, tried a totally different graphics plugin to see if it's specific to the one I happen to use (JQuery Flot), but jqPlot shows exactly the same symptoms - so it's a generic issue.

No doubt the problem will disappear with Readium 0.9x, but if any genius has some ideas I can try before then, that would be appreciated.

Of course, solving the problem in iBooks is even harder as no-one seems to have any idea of debugging tools. Thank goodness for Readium within Chrome!


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