D3 mouse broadcasting out of sync

When I tried the suggested setup from isboxer to have one big main window with 3 smaller ones, the mouse regularly gets out of sync on the other windows and your characters run in different directions. If you fidget around enough you can get the cursors back in sync, but it takes forever and will just wind up getting out of sync again.

I wound up having to create 4 windows of the same exact size to fix that from happening.

Is this expected behavior? I double-checked the smaller windows and in d3 they were the same resolution as the big main window.

No, of course that's not expected or desired behavior. What fullscreen/windowed mode are they in? (in the game, I know ISBoxer puts it in a window) That will make a difference in the behavior, and switching to another may prevent it. If that narrows it down any, let me know so I can try to reproduce.

Changing from windowed mode to windowed full screen mode fixed it, thanks.