What are the major differences in API and functionality of Windows Forms between .Net framework versions 2.0, 3.5 and 4.0?
If you implement an application (windows form), which .Net framework version will be your choice? My target deployment machine will be 60% in windows XP and 40% in windows7. My current choice is .Net 2.0.
Winforms has been feature-complete since .NET 2.0 (VS2005). The team that worked on it exists in name only, most of the team members switched to WPF. Only critical operating system compatibility and security fixes have been released since 2.0. I'm only aware of a change in SendKeys to make it work better in Vista. And an update to Open/SaveFileDialog to make it use the native Vista IFileDialog interface. Designer error handling was improved in VS2008.
Some late additions that are not technically part of Winforms nor are included with the framework download but otherwise work well in a Winforms app are the Visual Basic Power Pack controls, the Chart control and the Windows API Code Pack.
Since the introduction of WPF in .NET 3.0, WinForms as an old technology almost remains the same. So if you choose .NET 2, there won't be a big problem.
However, noticed that Microsoft no longer supports .NET 2 alone (you must use .NET 3.5 SP1), so to be safe, .NET 3.5 SP1 and .NET 4+ are the recommended options.
