Add "add to selection" capability to detail history window

[AM909]

In r5181:

After selecting an object in the History list window and clicking Show, the detail comparison window for the object appears. I would like a button at the bottom of the window (hopefully with a hotkey) to add that object to the current selection.

This is helpful in the licensing workflow, where one might select several ways, click show to bring up several detail windows to examine, and then go through them, needing to select some to mark clean and others not.

It would also be nice if the first detail window would come up in the same position as the last one closed so one could start the cascade further toward the top left corner, allowing more windows to fit than currently.