VB Migration Partner’s support library hides most of the differences between the VB6 and the .NET versions of the MonthView control, but not all of them. In most cases the remaining differences should have no impact on migrated programs. Here’s their complete list:

1. The BackColor property has no effect and has been made obsolete, even though it correctly retains the value that you’ve assigned to it via code. Notice that the VB6 versions of this property only affects the color of the bottom row of pixels in the control, therefore chances are that you never actually intentionally assigned this property in your VB6 code. (You change the actual background color by means of the MonthBackColor property, not the BackColor property.)
2. The Appearance and BorderStyle properties have no effect and have been made obsolete. More precisely, they always return the value 1-cc23D and 0-cc2None, respectively, and throw an exception if you assign them a different value. (The exception is thrown only if the VB6Config.ThrowOnUnsupportedMembers property is True.)
3. The DateChanged property is set to True when a new value is assigned to the Value property, as in VB6. However, in the converted VB.NET application the Value property is assigned behind the scenes more often than in VB6, therefore you might find that the DataChanged property becomes True under certain circumstances in VB.NET but not in the original VB6 application.
4. When you click on the year number portion of the VB.NET MonthView control, no mouse event is fired.