Multi monitor weirdness

[ch...@bucketobits.com]

I'm developing a DirectX app that can run fullscreen. It usually
works fine, but when running with multiple monitors, I get some weird
results when the user uses the mouse. I'd prefer to just constrain
the mouse cursor to the DirectX monitor, but I can't figure out how to
do that without using mouse capture (which I'd rather not do).

If the user drags the mouse off the DirectX monitor and clicks on the
other monitor, the app goes through a few minimize/refresh loops
before again showing the DirectX surface. But then dragging the mouse
back over there has no effect. The cursor gives focus to the apps
underneath the surface and clicking causes another few draw/minimize/
refresh cycles. The only thing I can do at this point is kill the
app.

I tried to determine what messages the app is getting that is telling
it to minimize/refresh, but all the messages are in the 0xC000 range,
which I can't find documented anywhere. My application doesn't
process them, it sends them onto the default message processor.

Anyone familiar with what's going on? Anyone know how to resolve this?