Nullability of reference types in type of parameter 'x' of 'int StripListItemComparer.Compare(object x, object y)' doesn't match implicitly implemented member 'int IComparer.Compare(object? x, object? y)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'y' of 'int StripListItemComparer.Compare(object x, object y)' doesn't match implicitly implemented member 'int IComparer.Compare(object? x, object? y)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'sender' of 'void StripListView.StripListView_DrawItem(object sender, DrawListViewItemEventArgs e)' doesn't match the target delegate 'DrawListViewItemEventHandler' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'sender' of 'void StripListView.StripListView_DrawSubItem(object sender, DrawListViewSubItemEventArgs e)' doesn't match the target delegate 'DrawListViewSubItemEventHandler' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'sender' of 'void StripListView.StripListView_DrawColumnHeader(object sender, DrawListViewColumnHeaderEventArgs e)' doesn't match the target delegate 'DrawListViewColumnHeaderEventHandler' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'sender' of 'void StripListView.StripListView_MouseClick(object sender, MouseEventArgs e)' doesn't match the target delegate 'MouseEventHandler' (possibly because of nullability attributes).

Non-nullable field '_selectedGroup' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_ColorData' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Dereference of a possibly null reference.