problem with closing application

i create my own dialog form with two buttons (ok, cancel) and checked开发者_如何学Go list box. i want to get all selected strings in first form which shown second form. for that purpose i do function GetSelected which return CheckedIndices->GetEnumerator() of my list box. now i want to deselect all strings on pressed cancel button. And deselect all strings on close form by pressing X in corner of form. how to track click the X?

how to track click the X?

You can use the FormClosed or FormClosing event