strange combo box edit problem with firefox 1.5

i am using firefox 1.5 with the trail release version.

this is what my grid look like :

http://pic3.picturetrail.com/VOL22/543225/1542139/137742148.jpg

i want to add editing to a column so i tried this:

var mycombo = new AW.UI.Combo;
mycombo.setItemText(["Home", "Favorites", "Font size", "Search"]);
mycombo.setItemCount(4);
obj.setCellTemplate(mycombo, 1);

and this is what the screen looks like:

http://pic3.picturetrail.com/VOL22/543225/1542139/137742152.jpg

has anyone seen this sort of behaviour?

and btw, i did try adding the combo on the grid.htm example and it looks fine. the only problem is the combo remains open and cannot be closed up.