http://imagej.273.s1.nabble.com/Open-Image-in-Existing-Instance-tp3692166p3692168.html
> High Reinhard,
>
> check "Run socket listener" in Edit>Options>Misc.
>
> From the 1.42p release notes:
> Added the "Run socket listener" option to the Edit>Options>Misc
> dialog. Enabling this option prevents multiple copies of ImageJ from
> starting but it can cause a security alert when ImageJ starts.
>
> From the online documentation:
> Enable Run socket listener and ImageJ will use sockets to prevent
> multiple instances from being launched. On Windows, this avoids the
> problem where another copy of ImageJ starts each time an image is
> dragged and dropped on the ImageJ icon. It also prevents multiple
> instances when running ImageJ from the command line. Note that you
> may get a security alert the first time ImageJ starts with this
> option enabled. ImageJ does not require external socket access so it
> is okay to deny it access in the security alert.
>
> Michael
> ________________________________________________________________
> Michael Schmid email:
[hidden email]
> Institut fuer Allgemeine Physik, Technische Universitaet Wien
> Wiedner Hauptstr. 8-10/134, A 1040 Wien, Austria
> Tel. +43 1 58801-13452 or -13453, Fax +43 1 58801 13499
> ________________________________________________________________
>
> On 10 Jun 2009, at 17:04, Reinhard Mayr aka Czerwinski wrote:
>
> > Hi on the list,
> >
> > since the update to ImageJ 1.42q I experience an unpleasant
> > behavior of ImageJ.exe (WinXP): Every time I open an image fron the
> > explorer by double-clicking, a new instance of ImageJ is started.
> >
> > This is quite nasty and used to be different. In former versions of
> > ImageJ all files were opened in the same instance. Is it possible
> > to go back to the previous mode?
> >
> > Cheers,
> >
> > Reinhard.
> >