Implement play/stop cap and shell music

test/imgui/misc/cpp/README.txt

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+
+imgui_stdlib.h + imgui_stdlib.cpp
+  InputText() wrappers for C++ standard library (STL) type: std::string.
+  This is also an example of how you may wrap your own similar types.
+
+imgui_scoped.h
+  [Experimental, not currently in main repository]
+  Additional header file with some RAII-style wrappers for common Dear ImGui functions.
+  Try by merging: https://github.com/ocornut/imgui/pull/2197
+  Discuss at: https://github.com/ocornut/imgui/issues/2096
+
+imgui-module:
+  C++20 module binding
+  https://github.com/stripe2933/imgui-module
+
+See more C++ related extension (fmt, RAII, syntactic sugar) on Wiki:
+  https://github.com/ocornut/imgui/wiki/Useful-Extensions#cness