Windows not movable with .NET 10

[RickStrahl]

Describe the bug

When compiling for .NET 10 (preview) MetroWindow are not responding to drag move operations. Windows are hard stuck.

Happens to top level and child windows. Non-Metro windows move as expected.

Window sizing is working - only moving seems to be affected. Both manual dragging and via Window Move menu - neither moves Mah window.

Same code compiled for .NET 9.0 works as expected.

Steps to reproduce

• Create a simple WPF app
• Add a Window
• Run
• Sizing works
• Change window to MetroWindow
• Run
• Sizing 'stuck' - Window not movable

Environment

MahApps.Metro version: v2.4.10
Visual Studio: 2022 17 (latest)
Markdown Monster v3.9.7.3
.NET 10.0.0-preview.6.25358.103 • x64
Microsoft Windows 10.0.26100 • x64 • en-US

[timunie]

I wonder if MahApps v3 preview package would solve the issue. It uses newer ControlzEx. But it has some breaking changes and therefor it may not be easily pluggable into MarkdownMonster 🤔

[RickStrahl]

Is v3 ever going to see the light of day? Looks like MahApps is stuck in the mud here...

Weary to muck with it at this stage.

But hoping this issue can get resolved in 2.x - that's a major breaking issue.

Just checked the latest preview (preview.7) and the issue is still there, so not some fluke.

[RickStrahl]

So I double checked MahApps 3.0 RC and it exhibits the same behavior unfortunately. Windows are not movable.

Plain window with base styling and nothing else added in a new project. 🥲

[punker76]

I didn’t tested MahApps or ControlzEx with .Net 10. I will try to take a look. Maybe @batzen has already an idea.

[batzen]

The "offender" is

MahApps.Metro/src/MahApps.Metro/Controls/MetroWindow.cs

Line 1465 in e4bb760

var value = typeof(Window).GetProperty("CriticalHandle", BindingFlags.NonPublic | BindingFlags.Instance)?.GetValue(this, new object[0]) ?? IntPtr.Zero;

CriticalHandle got renamed to Handle.
Instead of using reflection the code should better use WindowInteropHelper to get window handle.