max2027 crashes when using maxscript to display a WPF window

[lgedZV4XV]

In 3dsmax 2027, any WPF window created with maxscript will crash when show it, for example:

(dotnetObject "System.Windows.Window").Show()

[denisT.MaxDoctor]

Confirm it again: the only real option is to use ElementHost. I would estimate the chances of success at around 90%.

Technically, I don’t see any major difficulties. Windows Forms should work.

[spacefrog_]

Just tested against the just released 3ds Max 2027.1 update and sadly IT'S not FIXED !!!

[Mr.Drm]

(
    xamlstring = "
    <UserControl
        xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
        <Grid Margin='10'>
			<TextBlock Text='Hello from WPF'/>
        </Grid>
    </UserControl>
    "
    form = dotnetobject "system.windows.forms.form"
	form.text = "WPF in ElementHost"
	
    elementhost = dotnetobject "system.windows.forms.integration.elementhost"
    elementhost.child = (dotnetclass "system.windows.markup.xamlreader").parse xamlstring
    form.controls.add elementhost
    form.show()
)

I ran this simple script and 3ds Max 2027 crashed just as it did without using ElementHost!
Guys, please fix this issue as soon as possible – my working scripts are now useless!

[denisT.MaxDoctor]

Nice snippet 👍

try this one:

(
    xamlstring = "
    <UserControl
        xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
        xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
        <Grid Margin='10'>
			<TextBlock Text='Hello from WPF'/>
        </Grid>
    </UserControl>
    "
    form = dotnetobject "MaxCustomControls.Maxform"
	form.text = "WPF in ElementHost"
    elementhost = dotnetobject "system.windows.forms.integration.elementhost"
    elementhost.child = (dotnetclass "system.windows.markup.xamlreader").parse xamlstring
    form.controls.add elementhost
    form.Show() 
)

dotnetobject "MaxCustomControls.Maxform"

[MartinBeh]

---

@denisT.MaxDoctor wrote:

Nice snippet 👍

try this one

---

At least for me, this also does not work. Same thing: freeze of UI, no error message, crash to desktop.

[denisT.MaxDoctor]

Do you like using XAML as your source for WPF? That’s perfectly fine; I just want to narrow the scope a bit...

[denisT.MaxDoctor]

I roughly understand how the breakage happens, what exactly Max breaks, and how it happens. I want to start the process so that by the time this breakage occurs, all internal structures are already properly initialized.

[denisT.MaxDoctor]

Could you please tell me exactly which step causes the freeze and crash?

[denisT.MaxDoctor]

After crashing the recent snippet, the chances of final success drop dramatically 😄 I guess the problem leaks into the WPF dispatcher afterward.

But even that is not fatal yet… what really matters is that the problem does not sink to the rendering level. If it does, then we’ll probably just have to throw our hands up.

[MartinBeh]

Well... the line that crashes is 

form.Show()

Not sure what else I can tell you?

[Mr.Drm]

Yes, all my scripts have pure XAML UI.

[Mr.Drm]

Thanks, but it doesn't work 😞

[Mr.Drm]

This is the worst news I've heard in a long time... I hate maxscript UI controls, and rewriting all my tools to use it would be suicide for me...

[denisT.MaxDoctor]

I don’t like rollout UI controls either, but for over 25 years they’ve somehow remained the only “correct” option... meanwhile, all my tools from the early 2000s are still alive and working perfectly fine in all versions.

[denisT.MaxDoctor]

---

@MartinBeh wrote:

Well... the line that crashes is 

form.Show()

Not sure what else I can tell you?

---

one more test (please tell the moment of the crash):

	
(
	xamlstring = @"
	<UserControl
		xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
		xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
		<Grid Margin='10'>
			<TextBlock Text='Hello from WPF'/>
		</Grid>
	</UserControl>
	"

	form = dotnetobject "MaxCustomControls.Maxform"
	form.Text = "WPF in ElementHost"
	elementhost = dotnetobject "System.Windows.Forms.Integration.ElementHost"
	form.controls.Add elementhost

	form.Showmodeless() 
	---form.Close() 
	

	elementhost.Child = (dotnetclass "System.Windows.Markup.XamlReader").parse xamlstring

)

(
	try(form.close()) catch()

	form = dotnetobject "MaxCustomControls.Maxform"
	form.Text = "WPF in Form"	

	form.StartPosition = form.StartPosition.Manual
	form.Location = dotnetobject "System.Drawing.Point" 200 100
	form.Size = dotnetobject "System.Drawing.Size" 400 200
	form.BackColor = form.BackColor.Red	
		
	panel1 = dotnetobject "Panel"
	panel1.Dock = panel1.Dock.Fill
	panel1.BackColor = panel1.BackColor.Red

	panel2 = dotnetobject "Panel"
	panel2.Height = 40
	panel2.Dock = panel2.Dock.Top
	panel2.BackColor = panel2.BackColor.Yellow

	ehost = dotnetobject "Integration.ElementHost"
	ehost.Dock = ehost.Dock.Top
	ehost.Width = 100
	ehost.Height = 20

	wpb = dotnetobject "System.Windows.Controls.ProgressBar"
	b = dotnetobject "System.Windows.Media.SolidColorBrush" ((dotnetclass "System.Windows.Media.Color").FromRGB 255 0 0) 
	wpb.Foreground = b
	wpb.Width = 100
	wpb.Height = 20
	wpb.Value = 50
	ehost.Child = wpb

	panel2.Controls.Add ehost
	form.Controls.Add panel2

	form.showmodeless()
)

... and this one:  

[Mr.Drm]

first test:

elementhost.Child = (dotnetclass "System.Windows.Markup.XamlReader").parse xamlstring //<--- crash on this line

second test:

form.showmodeless() //<--- crash on this line

[Mr.Drm]

Well, not all interfaces can be built with MaxScript controls. For example, I have an XALM UI, and the business logic is in MaxScript. Everything worked fine until 3dsmax2027.

[denisT.MaxDoctor]

I don’t mean any unique UI cases. In this situation, anything that works is good enough — WPF, .NET, Qt, whatever.

But if you start overcomplicating things just because you want to make the interface fancy, be ready for it to become a problem sooner or later.