I'll probably be using your extension in basic forms. I was wondering it there's a reason why you don't use the default combo classes "x-combo-list", "x-combo-list-inner", "x-combo-selected". As I use the gray theme, I noticed that by using those classes along with "x-checkboxcombo-list" and "x-checkboxcombo-list-inner" and getting rid of all the colored stuff in the css file, it looked like a normal extjs combo.
I might be creating selectAll() and selectNone() methods for it as well, but my knowledge of ExtJS isn't that great, so I'm not sure if it's a good idea that I share my perhaps-crappy code
Oh and is there a reason why we should use your extension instead of Saki's LOVCombo ? I know they work differently, as stated in your first post, but I'm still wondering if I should use yours or his...