In a grid form , in edit mode, the contextual menu and associated functions of the columns are no longer available since version 5.0. I do not speak English very well, but it seems to me it looks like the bug 93437 , fixed since 5.0.2 . I'm on 5.0.4 , and I still have the problem ( windows7 )
*** This bug has been marked as a duplicate of bug 96482 ***