A window with WindowChrome flickers during the resize operation if the content is WindowsFromsHost

[AndreyMarten]

• .NET Core Version: 6.0
• Windows version: 21H2 (OS Build 22000.318)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: Yes

A window defined with WindowChrome flickers during the resize operation if the content is the WindowsFromsHost element. The screencast and project illustrate the problematic behavior.

Screencast
sample.zip

The WpfApp1 project is a .NET project that hosts a UserControl1 from WinFormsLibary1 (also .NET). Please run this project to replicate the issue.

The DXSample project is a .NET Framework project that hosts a UserControl1 from WindowsFormsControlLibrary1 (also .NET Framework). In this project, you can see that the issue occurs in .NET Framework as well.

[maximilien-noal]

Windows Forms uses software rendering and it's going to flicker on resize in this context or if OnPaint() is slow enough,

Please use WPF instead. WPF uses hardware rendering and has therefore smooth rendering.

A very similar issue has been already labeled as "WON'T FIX' in the past :
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/957d58bb-95f4-4bf0-9f87-aef55b564af8/windows-forms-host-in-wpf-application-flicker-on-visibility-change?forum=wpf

Quote :

WPF and windows forms use different display technology.

These things are oil and water.

You could try reducing height and width of the containing control using an animation so you turn a problem into a feature. Just miss out the "from" and set the "To" to 1 or something and do 2 doubleanimations. One for height and one for width.

Reduce the size then collapse visibility.

If you don"t want flickering, you have to use WPF. It has been made precisely to fix that problem (among others).

WindowsFormsHost is there so you can use existing 3rd paty WinForms controls or in-house WinForms controls that you'd like to use with WPF. It's meant to aid the transition to WPF. But if you can, only using WPF is the better choice.

This way, you'll also avoid the AirSpace problem :
#152