Panel buttons - create new process or restore existing?

[Ian Collins <ianc kcbbs gen nz>]

Can a panel launcher button check whether the application is already
running (e.g. minimized) and if so restore it without starting another
instance?
(or is it the responsibility of the app started to detect and restore
running instances?).

E.g.
I start gnucash from a panel launcher button.
When finished I minimize gnucash.
My wife comes along and hits the gnucash panel button again. What I
want is the existing gnucash to restore itself. What I get is an error
from gnucash saying the app is already running.

Many regards,
Ian Collins.