Gtkmm3 and flatpak

Hello guys, I’ve made an app and I wanna package it as a Flatpak. My app has been written in C++ using gtkmm3 toolkit (C++ wrapper for GTK3). i use a simple g++ command for compiling my application. but when i run the build command inside Flatpak builder it complains about that gtkmm does not exist.

Which runtime and sdk should i use to properly build my app?

runtime: org.gnome.Platform
runtime-version: '41'
sdk: org.gnome.Sdk


gtkmm is not in the SDK, You have to build it first, there are already a few apps that do that, including Gnote, Inkscape, etc.


Oh, I see, Thank you for your help.