Thanks for your comments about EmEditor.
As for rhtml/ruby append symbol (<<), maybe you can post a sample code where the problem happens, or you can email me a file at firstname.lastname@example.org, and I will make sure to consider the issue in future versions.
You can find additional themes in the library http://www.emeditor.com/modules/mydownloads/viewcat.php?cid=13
I will also try to modify the default themes in the future.
I might also consider the missing feature where you can select a word to highlight the word, and every other instance of it is highlighted.
And I will also try to improve the keyboard search ability.