procedure TMainForm.ShellListViewMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var Item : TListItem;
begin
if (Button!=mbRight) or (OtherCondition) then exit;
Item := List.GetItemAt(X,Y);
if not Assigned(Item) then exit;
ShellListView.ShowContextMenu(ShellListView.ClientToScreen(Point(X,Y)));
end;