Why several ImageJ instances?

[vischer]

I made some tests on Windows XP and found following:

Each time I double-click the ImageJ microscope icon, a new instance of ImageJ is opened, painting another ImageJ main window exactly on the top of the previous. This is also true if I check Edit>Options>Misc..>Run Single Instance Listener.

ImageJ seems to be an exception; I cannot reproduce this with other (Java)applications. ImageJ on the Mac behaves well.

I think that having the same application open more than once creates a lot of confusion (multiplied by the number of students in an image processing course).

I also wonder why the "Single Instance" checkbox is not on by default (so at least dragging an image onto the microscope icon would behave well).

Wouldn't it be better to avoid more than one instances at all?

Norbert Vischer
Centre for Advanced Microscopy
University of Amsterdam
Netherlands

[dscho]

Hi Norbert,

On Sat, 5 Feb 2011, Norbert Vischer wrote:

> Each time I double-click the ImageJ microscope icon, a new instance of
> ImageJ is opened, painting another ImageJ main window exactly on the top
> of the previous.

That is intended behavior.

> This is also true if I check Edit>Options>Misc..>Run Single Instance
> Listener.

That is a bug.

> I also wonder why the "Single Instance" checkbox is not on by default
> (so at least dragging an image onto the microscope icon would behave
> well).

The reason is that the single instance listener of ImageJ listens on
sockets not caring whether somebody connects to that socket from the same
computer or from Sidney, Australia.

I tried to fix this some time ago, and it is in ImageJA (where the
single-instance listener is on by default), but somehow it did not work on
Wayne's computer, so it never made it into ImageJ.

Ciao,
Johannes

[Rasband, Wayne (NIH/NIMH) [E]]

On Feb 5, 2011, at 3:53 PM, Norbert Vischer wrote:

> I made some tests on Windows XP and found following:
>
> Each time I double-click the ImageJ microscope icon, a new instance of ImageJ is opened, painting another ImageJ main window exactly on the top of the previous. This is also true if I check Edit>Options>Misc..>Run Single Instance Listener.

The "Run single instance listener" option in Edit>Options>Misc.. should work as expected in the 1.45a8 daily build.

-wayne

> ImageJ seems to be an exception; I cannot reproduce this with other (Java)applications. ImageJ on the Mac behaves well.
>
> I think that having the same application open more than once creates a lot of confusion (multiplied by the number of students in an image processing course).
>
> I also wonder why the "Single Instance" checkbox is not on by default (so at least dragging an image onto the microscope icon would behave well).
>
> Wouldn't it be better to avoid more than one instances at all?
>
> Norbert Vischer
> Centre for Advanced Microscopy
> University of Amsterdam
> Netherlands

[Norbert Vischer-2]

> The "Run single instance listener" option in Edit>Options>Misc.. should work as expected in the 1.45a8 daily build.
>
> -wayne


Thanks, Johannes and Wayne.

Having the single-instance listener switched on by default (like in ImageJA) is a good choice. Also Mac and Windows behavior will be the same.

Currently, if Windows is set to associate ".tif" files with ImageJ, each double-click on a ".tif"  file opens a new ImageJ instance (unless the user explicitely has checked that hidden checkbox).
A new user may not even be aware of this complicated situation - nor understand the "Instance" checkbox hidden in Edit>Options>Misc..
So hopefully the default will be set to "single-instance".

Norbert Vischer
Centre for Advanced Microscopy
University of Amsterdam
Netherlands