Hive: HKEY_CURRENT_USER
Key: Control Panel\Mouse
Name: ActiveWindowTracking
Type: REG_DWORD
Value: 1
The X window system has another neat feature called "snap to". When this feature is enabled, the mouse snaps to the default button upon alert or dialog windows. Try it, you may like it. To enable:
Hive: HKEY_CURRENT_USER
Key: Control Panel\Mouse
Name: SnapToDefaultButton
Type: REG_DWORD
Value: 1