I'm sorry to see that no one helped me, I was hoping there were a comunity ?

Fortunately I found a solution (by myself ).

Moreover I would like to say that I also notice a bug on jqgrid.

Please try this test:

-On a multiple selection do a clic on all rows (except header) to check it

Then

-Do a click on header checkbox (will do nothing because all rows should have already been selected).

-Unselect all rows by clicking on each checkbox (except header one).

You should have no row selected and should have checked header checkbox

Try to click on “Get Selected id's” you will have an id even though no row is selected 😉

You can try here: http://trirand.com/blog/jqgrid…..qgrid.html