Thinking you could tell the original sized target window to shrink to smaller size by making a smaller version of the window that is only visible when /onshow impliedtarget window is initiated. Then, have the onshow event show both the smaller target and the implied target as you stated side by side. Once the implied target is no longer avail, the on hide event would hide both the implied target and smaller version target windows, allowing an on show event to display the original sized target window you used.
If that makes any sense....