1) You can't put double quotes inside double quotes. Use single quotes.
2) Try something like this:
Code:
<button onclick="document.body.filters.item('DXImageTransform.Microsoft.Matrix').M11 = 0 - document.body.filters.item('DXImageTransform.Microsoft.Matrix').M11;
document.body.filters.item('DXImageTransform.Microsoft.Matrix').M12 = 0 - document.body.filters.item('DXImageTransform.Microsoft.Matrix').M12;">Test</button>
This was pretty much gleaned from msdn.org, and since I haven't got IE to work with wine yet, I couldn't test it.
3) Don't depend on this, it's IE5.5+ only.
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