to simplify planning, I would like to be able to "pause" activities as soon as they are created, so that they do not enter the load. keep the "pause" mode when they are assigned and finally release the "pause" mode when they go "in progress". I manage to do it, except for the first "saved" state where it is impossible to have the "pause" boolean active by default. could you help me ?
Only solution will be to use the Screen Customization plugin.
Then, just define default value to "1" for objects Activity and Activity - Progress
(you have to do this on both as these values are duplicated and synchonized only through Status or Interface changes)
I try with "true", It seems to work, but when I create a new activity, with first workflow "Enregistré", the "mettre en pause" is not at true value ???
I put by defaut value on true, both : Activity / "mettre en pause" and Activiy-Progress / "mettre en pause"...
In fact, expected value in "on"
My fault, I tested and entered "on" but wrote "1" in the post.
I need a week-end... 
it's works thk you. But now, when i change the workflow to "assigné" it keep the "on" boolean state ...
normaly on "assigné" status, it will not on ...
Then default value for "pause" should be
###EVAL### ($this->idStatus==1)?1:0
and you must set pause to "readonly"
I tested, it works
in both object ? activity an activity-progress ?
Well, well, well ...
Formula is not the same for both, but both are required
For Activity 
###EVAL### ($this->idStatus==1)?1:0
For Activity - Progress 
###EVAL### (SqlList::getFieldFromId('Activity', $this->refId,'idStatus')==1)?1:0;
Easy ! 