Replicant dragger not drawn/erased

[humdinger]

This is hrev46610.

When you've dragged the replicant of ActivityMonitor onto the Desktop and disable "Show replicants" in the Deskbar, the dragger doesn't get erased until you waggle a window over it. Likewise, re-enabling "Show replicants" won't draw the dragger until you force it by waving a window over it.

As it all works on the non-replicant ActivityMonitor app, I guess the issue appears with the use of a transparent background by the replicant.

So, maybe not an issue specific to ActivityMonitor. I'll put in that category anyway for now. Feel free to move...