MotionState weirdness

[kate]

Hi,

I'm trying to hack the BasicDemo code to see if I can reproduce a problem I'm getting with kinematic objects. My first step was to replace the btDefaultMotionState with my own - which made everything go stretched and sideways. So, I started stripping the code from the btDefaultMotionState away to morph it into my own... and found that if I try to remove either of "m_centerOfMassOffset" or "m_startWorldTrans" (or the initialisation of the latter in the constructor), the cube stack explodes! Which seems a little odd to me.

I've attached the modified demo source; can anyone replicate this issue?
Or am I just having an attack of Friday-afternoon-ness?!

Yours befuddledly,

Kate