Those are standalone ready-to-build applications to demonstrate ImGui.
Unfortunately in 2015 it is still a massive pain to create and maintain portable build files.
I choose to provide Visual Studio 10 .sln files and Makefile for Linux/OSX. 
Please let me know if they don't work with your setup!
You can probably just import the .cpp files into your own system and figure out the linkage from there.

opengl_example/
    OpenGL example, using GLFW + fixed pipeline.
    This is simple and should work for all OpenGL enabled applications.
    Prefer following this example to learn how ImGui works, because it is the simplest shortest one!

opengl3_example/
    OpenGL example, using GLFW/GL3W + programmable pipeline.
    This uses more modern calls and custom shaders.
    I don't think there is an advantage using this over the simpler example, but it is provided for reference.

directx9_example/
    DirectX9 example, Windows only.
	
directx11_example/
    DirectX11 example, Windows only.
    This is quite long and tedious, because: DirectX11.
	
ios_example/
	iOS example.
	Using Synergy to access keyboard/mouse data from server computer. Synergy keyboard integration is rather hacky.

sdl_opengl_example/
	SDL2 + OpenGL example.

allegro5_example/
	Allegro 5 example.