> One thing that bothers me is that modifying the default engines; removing tracking parameters for example, results in a 'name already exist' error. Which is bizarre.

That's a definite bug that must have popped up when I added the ability to change the name. I'll fix that today.

(edit) 6-13
v1.6.0.3 should fix the problem

> 1) Javascript/Bookmarklet support.

(edit 6-15) Ready for v1.6.1

>Edit:
>Use short javascript snippets for more advanced local operations e.g. Find&Replace all instances of a word in a text box or copy and format selected text as bbcode, etc.

Are you wanting to access bookmarklets from the context menu when using the option to manage search engines via bookmarks? If you have a github account, start a new topic at the support site so I can get more info.

> 2) Search button: Save search history / always show last query
> 3) Search button: Make autocomplete optional

(edit 6-14) Ready for v1.6.1

> 4) Search button: Match browser theme

(edit 6-14) Having some problems with this one. Can't seem to get color values for built-in themes like Dark. I'll keep on it.

> 5) Search button: Support middleclick
Ready for v1.6.1