I have used this accepted answer to install Mono 5.2.0 to the Raspberry Pi 3. But I don't know how to install monodevelop or other ide to the Rpi3, because sudo apt-get install monodevelop doesn't work anymore because of those settings in the accepted answer. Any idea?
i found this link which explains the process i think but i haven't tried it for myself (yet).
you need to add the mono repository using the commands shown (see link) and then you can just do sudo apt-get install monodevelop
hope this helps.