the reason for the explicit size is so the page can be layed out 
correctly. using a 100% size will break the layout. Regardless , this 
will all be revamped in the Ajax view in Ansel 4.

While viewing the picture the configuration setting 
$conf[screen][width] and $conf[screen][height] set the actual size of 
the picture that will be displayed.

What I'm proposing is that would be set to be the maximum size of the 
picture on the screen and not the actual size.

This is partly a bug too because if it's set too big, the picture will 
go under the menu at the right. Too small you just can't view it 
correctly.

while displaying, the img tag is set like this

<img id="ansel-photodiv" width="2592" height="1936" 
src="http://mail.spagi.net/ansel/images/.horde/ansel/22/screen/22.jpg" 
style="">

I've tried to modify it live in chrome with

<img id="ansel-photodiv" width="100%" height="100%" 
src="http://mail.spagi.net/ansel/images/.horde/ansel/22/screen/22.jpg" 
style="">

and this actually work better as the picture will change size 
following the size of the browser and thus will look great on 
different resolution. I unfortunatly have absolutly no idea where to 
make this modification in the code of wither ansel or horde to change 
de view like this.