Thank you for your response. I ran "clickable create" and entered this option:
 main-cpp - C++/QML App (built using CMake with a main.cpp)
My project name is "mytest". I ran "clickable" and my USB connected tablet running Ubuntu Touch shows the app with "Hello World!". Good!
Next, I changed the main.cpp file so that is has the SDL test C++ code that you see in this posting. Also, I tried to make changes to the clickable.json file so the dependencies can be met, like so:
I saw clickable downloading the SDL2 files for armhf architecture. Looked good. But I get these error messages:
[ 90%] Linking CXX executable mytest
CMakeFiles/mytest.dir/main.cpp.o: In function
main': main.cpp:(.text+0xc): undefined reference toSDL_Init'
main.cpp:(.text+0x2e): undefined reference to `SDL_CreateWindow'
What should I adjust to get this test SDL test program working? Thanks!