Consistency with helper/modal windows and multiple desktops.

When focusing a window, bring its helper windows.  This happened before when
switching its desktop, but if you have 2 windows on different desktops and
switch between them, the helpers should come to both when they are being used.

When a new helper/modal window maps on a different desktop and you are using
the application, then the helper/modal window is moved to the current desktop
to be with the application you are using.