I would like to request a feature to allow named groups (or backreferences to more than 9 numbered groups).
A ticket on sourceforge [1] says (regarding replacement):
"Geany is limited to 9 groups in regular expressions. If you try to use a group after the 10th, it is replaced with the first group and the second digit of the group number. For example, if the group 1 is "first" and the 10 group is "tenth", \10 is replaced as "first0".
It seems that it is not possible to reference more than 9 numbered capture groups in the regular expression _replace_ field, even though Geany allows it in the regex _search_ field. In the search field, \10 is recognized correctly.
[1] https://sourceforge.net/p/geany/bugs/1042/