Dereference of a possibly null reference.

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.IndexOf' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.get_Item' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.RemoveAt' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.set_Item' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Dereference of a possibly null reference.

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.IndexOf' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.RemoveAt' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)

Make 'PaneCollection' sealed (a breaking change if this class has previously shipped), implement the method non-explicitly, or implement a new method that exposes the functionality of 'System.Collections.Generic.IList<T>.get_Item' and is visible to derived classes (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1033)