This can be done by prepending the string "(?i)" to the regex entered by the user. They could do this themselves, but I suspect lots of people would prefer this to be the default. We could have a new checkbox menu item under Vars, "Case-sensitive filtering", if anyone really prefers case-sensitive for some searches.
Fix issue #35 by adding menu item "Case sensitive search"
By default it is enabled. When disabled, regexes entered in doc-tf
box are matched case-insensitively by prepending them with "(?i)".