Thanks for fast answer,
Oh yes, in compiled source, it is enclosed in correct scope (i looked in src code).
global is probably not the good term, but there is really a conflict with tihs variable.
This is my case :
the user edit a row in a grid A.
The edit form has a link to open another dialog box with a grid B.
grid B has edit capabilities too.
just open this last edit form.
Close edit form, close grid B box,