Match `MxTransitionManager::SetupCopyRect`

[disinvite]

Not in the beta.

m_copyRect is probably an MxRect32. Converting it over and using GetWidth/GetHeight where they fit gives a slight accuracy boost.

You could get tricky with the mxgeometry functions like this:

m_copyRect = MxRect32(0, 0, m_waitIndicator->GetWidth(), m_waitIndicator->GetHeight());
m_copyRect += m_waitIndicator->GetLocation();

but I haven't found exactly what they used. It's tough to tell what's what in here because so much gets inlined.