Morning!
Have a look at this (from csurf_mcu.cpp):
bool IsKeyDown(int key)
{
if (m_midiin && !m_is_mcuex)
{
if (key == VK_SHIFT) return !!(m_mackie_modifiers&1);
//if (key == VK_SHIFT) return !!(m_mackie_modifiers&1);
if (key == VK_CONTROL) return !!(m_mackie_modifiers&4);
if (key == VK_MENU) return !!(m_mackie_modifiers&8);
}
return false;
}
I'll add a few more bits in a minute but thought I'd post this for now to save you looking in, possibly, the wrong place.
Edit: And this from reaper_plugin.h :
virtual bool IsKeyDown(int key) { return false; }
// VK_CONTROL, VK_MENU, VK_SHIFT, etc, whatever makes sense for your surface