She 'went into mourning' for her dead husband. [=she began to mourn for her dead husband]
She is still 'mourning' her husband, who died last year.
She is still 'in mourning' for her dead husband.
(..) She was a bold and gallant Green Lantern... ...whose achievements will long be remembered. But for now, we must set aside our mourning for the threat at hand. Glad you could make it. Sorry. We know from her ring that Ardakian's murderers were Shadow Demons. Soulless creatures (..)2011 Green Lantern: Emerald Knights