Feditext beta users: today's version 1.7.2 build 126 now supports editing posts on GotoSocial 0.18 (already supported for most other Fedi servers).
since GtS 0.18 is still in development, this release is recommended for advanced GtS users only: you need to explicitly set a version like 0.18.0-dev while building GtS for Feditext to detect and enable 0.18 features.
users of current GtS or other servers don't need to update to today's Feditext release.