I used an Ubuntu 14.04 VM to test this out.
- I took the sources of the [Geany 1.33 PPA](https://launchpad.net/~geany-dev/+archive/ubuntu/ppa), applied [your Geany patch](https://github.com/geany/geany/pull/1829) (I ignored the `GEANY_API_VERSION` hunk as that failed to apply), then built with `dpkg-buildpackage -us -uc -nc` and installed the resulting packages. I'm not sure if the Geany patch is still necessary though given the comments in the PR, and I see that you did a force push but I can't find the original commit hash to compare with. - I cloned your branch and built vimode, copied `vimode.so` to `~/.config/geany/plugins` and enabled the plugin in Geany.
I get the block cursor so it seems the plugin itself is enabled. However it does not seem to capture keys correctly, i.e. typing text inserts text, Ctrl-W closes the current tab and pressing keys when text is selected replaces the selection. Pressing escape does not seem to have any effect. I did not change the vimode options. Note that `viw` behaves the same way.
Feel free to ignore if it's clear that it's my fault.