Implement play/stop cap and shell music

test/imgui/examples/example_sdl2_opengl3/build_win32.bat

@@ -0,0 +1,8 @@
+@REM Build for Visual Studio compiler. Run your copy of vcvars32.bat or vcvarsall.bat to setup command-line compiler.
+@set OUT_DIR=Debug
+@set OUT_EXE=example_sdl2_opengl3
+@set INCLUDES=/I..\.. /I..\..\backends /I%SDL2_DIR%\include
+@set SOURCES=main.cpp ..\..\backends\imgui_impl_sdl2.cpp ..\..\backends\imgui_impl_opengl3.cpp ..\..\imgui*.cpp
+@set LIBS=/LIBPATH:%SDL2_DIR%\lib\x86 SDL2.lib SDL2main.lib opengl32.lib shell32.lib
+mkdir %OUT_DIR%
+cl /nologo /Zi /MD /utf-8 %INCLUDES% %SOURCES% /Fe%OUT_DIR%/%OUT_EXE%.exe /Fo%OUT_DIR%/ /link %LIBS% /subsystem:console