a) Linux Mint is based on Ubuntu. I have just looked at the software sources and ubuntu is included by default.. b) you may have markdown plugin installed by default see the following https://plugins.geany.org/markdown.html. and try the filtype set command as shown on the page. or else load a file with extension.md. After all geany handles some filetype out of the box. it does seem to me there may be a slight design error in disabling Tools->plugin manager for pre-installed plugins. I attach a sample.md file. with extension set as txt. It would help me if you could help me if you have the same issue on your setup. I would then feel happier knowing it is not just me. (README.md files are regularly associated with githib !!) Thanks in advance. [sample.txt](https://github.com/geany/geany/files/6143116/sample.txt)