Thread:Extension talk:WYSIWYG/Fatal error: Call to undefined method MediaWiki::getVal() in CKeditor.body.php (MW 1.23.3 + WYSIWYG 1.7.0)/reply

I have also tried 1.7.0 with MW 1.22, but it did not start there either so I gave up.

Perhaps you could try #6 bundle of downloads section to see if it is any good for you. I do not know what kind of differences there are with these two versions, I quess they are not identical anyway.

I have done a quick test with MW 1.23.3 and #6 bundle of WYSIWYG and I did not notice any problems. Bundle #6 has old WikiEditor of MW 1.22. If you would use "out of box" WikiEditor of MW 1.23.3 together with #6 bundle of WYSIWYG, switching between wysiwyg and mediawiki (source) modes does not always hide toolbar of WikiEditor properly.