There was a memory leak:
Code
Unfreed: 1082,    , 8 bytes
Unfreed: 1083,    , 876 bytes

In original and txesmi's examples, so I had to add this:
Code
void on_exit_event()
{
	sys_free(ImGui->lpVtbl);
	sys_free(ImGui);
}

void main()
{
	on_exit = on_exit_event;
        ....
}

Also, there is a typo (no space between ImGuiWindowFlags_AlwaysUseWindowPadding and 1) in imgui_enums.h, in line 35.
Code
#define ImGuiWindowFlags_AlwaysUseWindowPadding1 << 16 // Ensure child windows without border uses style.WindowPadding (ignored by default for non-bordered child windowsbecause more convenient)


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