I believe this is occurring because the GL context and the DX context are running on different devices. We might need to do some fancy stuff to get them to occupy the same one.

I have a test setup we can replicate this on, but we need to figure out if either:
a) the wrong GL device is being used
b) the wrong DX device is being used.

Would love some thoughts on how we can detect this.

I got the following in xaml designer using v3.2.2 from Nuget.

I am new to opentk so please forgive me,

I started a new WPF project and with the help of justin113d and lots of confusion later I was finally able to render to the wpf control.

However soon after I noticed that my 100x100 pixel image that I rendered as a texture to two triangles was blurry, I then noticed the edges of the wpf control had white lines down the side of it.

The control is 800x800 and the viewport is 800x800.

Taking a screenshot of the wpf control under the advice of jvbsl I was able to measure the control as 801x800, so resizing the control to 799x800 resolved my pixel blurred issues not only on the lines left+right of the wpf control but the rendered triangle texture as well.

Please let me know if you need further details.

Hello.

I just tried the latest version of glWPFControl,
It doesn't work properly on Parallels Desktop on Mac.

Is Parallels Desktop on Mac not supported?
My environment ↓

PC: iMac 2019 4K
GPU : AMD Radeon Pro 560X
Version of Parallels Desktop : 15
Virtual OS : Windows 11 Pro

Here is the error message ↓

And, GLWpfControl on Bootcamp may or may not work on some Macs.
(Both are Windows 11 Pro)

◯ It works on Bootcamp of iMac 2019.
(GPU : Radeon Pro 560).

✗ It doesn't work on Bootcamp of Macbook Pro 2015.
(GPU : Intel Iris Pro Graphics).

GLControl using WindowsFormsHost works on Bootcamp,
But there is a flickering problem when moving the View...
So I'd rather use GLWpfControl if possible !

Hi all. Thank you for excellent work. Easy to implement - very fast and convenient. For Apps with WPF and OpenGL it is a must.
I just want to indicate that the antialiasing as well as the stencil buffer are not working. These two features would be very welcome. As your PresentationParameters structure has already reserved members MultiSampleQuality, EnableAutoDepthStencil I presume that you have already plan to implement them. Looking forward to those features.

Hi!

I am loading image data using this control, and it works great, except my image is inverted in X and Y.

Is there a simple way to fix this? Code below:

public static int LoadTexture()
        {
            byte[] bytes = _gv.GetTextureBytes(frameNum);// grabs image data

            int tex;
            GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest);

            GL.GenTextures(1, out tex);
            GL.BindTexture(TextureTarget.Texture2D, tex);

        
            GL.CompressedTexImage2D(TextureTarget.Texture2D, 0, InternalFormat.CompressedRgbaS3tcDxt1Ext, width, height, 0, _gv.FrameBytes, bytes);


            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.Repeat);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.Repeat);

            return tex;
        }

        public static void DrawImage(int image)
        {
            GL.MatrixMode(MatrixMode.Projection);
            GL.PushMatrix();
            GL.LoadIdentity();

     
            GL.Ortho(0, width, 0, height, -1, 1);

            GL.MatrixMode(MatrixMode.Modelview);
          

            GL.PushMatrix();
            GL.LoadIdentity();

            GL.Disable(EnableCap.Lighting);

            GL.Enable(EnableCap.Texture2D);

          
            GL.BindTexture(TextureTarget.Texture2D, image);

            GL.Begin(PrimitiveType.Quads);

            GL.TexCoord2(0, 0);
            GL.Vertex3(0, 0, 0);

            GL.TexCoord2(1, 0);
            GL.Vertex3(width, 0, 0);

            GL.TexCoord2(1, 1);
            GL.Vertex3(width, height, 0);

            GL.TexCoord2(0, 1);
            GL.Vertex3(0, height, 0);

            GL.End();

            GL.Disable(EnableCap.Texture2D);
            GL.PopMatrix();

            GL.MatrixMode(MatrixMode.Projection);
            GL.PopMatrix();

            GL.MatrixMode(MatrixMode.Modelview);
        }



        public static void Render()
        {
            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
            texture = LoadTexture();
            DrawImage(texture);

        }

Problem:
I am using version 4.2.2 and am instantiating multiple GLWpfControls (my application can have multiple tabs with an OGL-based scene) and am encountering a stack overflow upon launching the other GLWpf controller. I've found the root cause of this to be related to the OnKeyUp/OnKeyDown functions that ultimately call RaiseEvent.

Some possible solutions:
I've worked around this in my local repo by checking if the event is handled or not. In my KeyUp/Down callbacks I've set the event's Handled property to true and I made the following edit:

In GLWpfControl.cs:

        internal void OnKeyDown(object sender, KeyEventArgs e)
        {
            if (e.OriginalSource != this && !e.Handled)
            {
                KeyEventArgs args = new KeyEventArgs(e.KeyboardDevice, e.InputSource, e.Timestamp, e.Key);
                args.RoutedEvent = Keyboard.KeyDownEvent;
                // \todo I am commenting out because I get an overflow here...
                RaiseEvent(args);
            }
        }

Note that I added the && !e.Handled and am flagging the event as Handled=true in my own key callbacks.

My working theory is that two GLWpfControllers get into an infinite loop by catching/raising the event until the stack overflows.

At the very least, could we get some kind of user-level setting to enable/disable the event handling to avoid this. Or even a setting in Start()'s to protect from this block:

EventManager.RegisterClassHandler(typeof(Control), Keyboard.KeyDownEvent, new KeyEventHandler(OnKeyDown), true);
EventManager.RegisterClassHandler(typeof(Control), Keyboard.KeyUpEvent, new KeyEventHandler(OnKeyUp), true);

Something like

            if ( _settings.RegisterKeyHandlers )
            {
                EventManager.RegisterClassHandler(typeof(Control), Keyboard.KeyDownEvent, new KeyEventHandler(OnKeyDown), true);
                EventManager.RegisterClassHandler(typeof(Control), Keyboard.KeyUpEvent, new KeyEventHandler(OnKeyUp), true);
            }

Hi,

I have .net framework 6.0 and GLWpfControl 4.2.2

I put GLWpfControl in a sub window, it works good for the first show the sub window, but when open the sub window for the second time, press the arrow keys (actually any key) will case System.StackOverflowException: 'Exception_WasThrown'

but there is no stack trace, and not event logs.
I believe something must be cleared on window closing, any advise?

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
            Window1 dialog = new Window1();
            dialog.ShowDialog();
        }
    }

public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            var settings = new GLWpfControlSettings
            {
                MajorVersion = 2,
                MinorVersion = 1
            };
            OpenTkControl.Start(settings);

            //GL.Enable(EnableCap.Blend);
            GL.Enable(EnableCap.DepthTest);
            //GL.Enable(EnableCap.ScissorTest);
        }
}

Hi, first of all, thanks for this very useful package, it solves some current issues with OpenTK and its dependencies and is very nice to use.

However, the control displays odd behaviour when it's resized. If put inside a Grid, and the Grid column is resized using a GridSplitter, the control will not update its size until the row is resized... and vice versa. Note: The parent control type seems to be irrelevant, this happens when parenting the GLWpfControl inside other container types, too.

Here's a screen recording (in GIF format) which shows the undesirable behaviour:
https://i.gyazo.com/972ae86b2ff91b09da3fa715075c2302.gif

I'm not sure if this is intentional behaviour, or can be solved via code (perhaps by invalidating something?), but it seems a little strange to me, and I'd probably consider it a bug... unless it's just the way I'm using the control

(Edit) Oh I should mention, in the GIF the magenta area is the control. The space above it is intentional.

I release resouces like

            GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
            GL.BindVertexArray(0);
            GL.UseProgram(0);

            // Delete all the resources.
            GL.DeleteBuffer(VBO);
            GL.DeleteVertexArray(VAO);
            GL.DeleteBuffer(EBO);

            GL.DeleteProgram(ActiveShader.Handle);

But this won't work.Everytime reopen the window that contains GLWpfControl.I got this exception:
"An unhandled exception of type 'System.ExecutionEngineException' occurred in OpenTK.Graphics.dll".

I was just playing with the GLWpfControl - testing for multiple monitors. Works well with extended monitors - one can drag from display to display. Switching monitor off is no problem.
It crashes, however, in the following scenario (my preferred configuration): Normally I work at FullHD - seeing on both the notebook monitor and external monitor the same stuff (displays are duplicated). When I close the lid of computer - the main monitor shows 4K. It was working fine with GLControl but not with GLWpfControl - yet.
The GLWpfControl.Example in such a case (no matter whether we close the lid or open it) freezes on some lock in PreRender function.
My application (when lid is closed or opened) crashes instead - on some Interop: Message=UCEERR_RENDERTHREADFAILURE (0x88980406).
I guess should be easy to reproduce for anyone.
Seems when the context is given - it is not able to change automatically to match the other monitor settings? But I only speculate here...

Hi,

I found this control that can't write .SwapBuffers();
Have a method to draw the mesh from buffer?

I get this error:
'Application' is a namespace but is used as a type Application

I receive this error in App.cs, installed with nuget, I installed the last pre-release ( 3 )

While issue #77 now does appear to be fixed, I still cannot use it when targeting .NET 6.0. Any attempt to ex. update the package from 4.1.0 through VS' NuGet Package Manager results in an error while restoring packages (no error code), causing the changes to be rolled back, plus error NU1202, saying that 4.2.1 is incompatible with net6.0-windows[...] and only supports netcoreapp3.1-windows.

Comparing compatible framework information for 4.1.0 and 4.2.1 on NuGet.org, the former is listed as compatible with netcoreapp3.1 (no suffixes) and lists several more computed target frameworks (including ex. net6.0-windows), while the latter only lists netcoreapp3.1-windows (with the suffix) and no computed target frameworks.

To (hopefully) reproduce:

• Create new WPF application project targeting .NET 6.0
• Add OpenTK 4.3.0 and GLWpfControl 4.1.0
• Follow the Readme's Getting Started section
• Project builds and runs fine

Then:

• Attempt to update GLWpfControl to 4.2.1
• Encounter aforementioned error NU1202

I guess this is also an issue with the updated build system, maybe (somewhat educated guess) due to it setting the target framework specifically as netcoreapp3.1-windows instead of the more generic netcoreapp3.1?

I created a primitive application (.NET Framework 4.6.1) by simply placing the GLWpfControl component in the WPF window.
BugDemo.zip

In the project settings, I specified that the application is 32-bit.

The screenshot below shows the result of calculating the sum of two variables before initializing the GLWpfControl and after initializing it. It can be seen that after initialization, there are problems in calculating the sum.

If I specify in the project settings that the application is 64-bit, then the amount is calculated correctly.

I use OpenTK 3.3.1, OpenTK.GLWpfContol 3.3.0

Sorry, I can't get to Discord via work, hopefully this is the right place to post -

Currently MakeCurrent doesn't work from other threads for rendering contexts - it throws a resource in use exception. This seems like it'd be worthwhile so you can spawn threads for texture loading and the like that can subsequently request the context. If there is a way to do this currently feel free to let me know (or if there's a better place to post requests).

Hello,
Could you please update the nugget package with the latest changes that expose the binding context from the last commit as of now ?
Thank you a lot !

Is it possible to use a transparent back color?

Could you make a class that implements GameWindow to be bindable/assignable to the wpf control?

Hi there and thank's for the great and fast control.
Is there any way to debug my application with some GFWpfControls in it with a tool like RenderDoc?
Is there any tool I can use to do that? I am not getting any information about the application in all tools I tried and I think maybe it's because of the DX<->OGL interop?

What can I do? I would really like to be able to debug my shaders to see 'what's in there' :).
Thanks

Ref: mono/SkiaSharp#745 (comment)
Copy of my comments from there and what i tried.

But it does have some problems, it doesn't really seem to like rendering two dock windows (AvalonDock) it gets confused.

Some elements suddenly stop showing up, swapping back and forth when zooming.
When I hide my grid element (basically just rendering a bunch of lines) it partially comes back, but other things bug out.

Definitely related to GL, if I swap back to SKElement it renders normally again.
I'm using one SKGLWpfControl per window, and it messes up pretty badly.
If I use SKElement for both it works fine.
Hacky workaround, use SKGLWpfControl for the first Map window, and SKElement for all further created Map windows.
https://github.com/WolfCorps/TacControl/blob/bba4d364548fc18a29d29b2138a8e44de619f7d2/src/DesktopClient/Misc/MapControl.cs#L547-L559
Works nicely too, but of course is missing the performance improvement on the second window.

WolfCorps/TacControl@a90164a
Here is my code, didn't make any changes to SKGLWpfControl itself. I assume the issue is inside OpenTK.GLWpfControl

Edit: I thought this might be the problem.

Changing the code to manually get the correct window handle via Application.Current.Windows, also not better.
Two contexts in two seperate windows will confuse eachother.
Out of ideas at this point, but I also don't really know GL nor any of this code.

I don't have time currently to make a simpler repro, without maybe SkiaSharp/Mapsui/AvalonDock.

just one grid contains one GLWPFControl.But use code like this(code from Learn OpenTK project .https://github.com/opentk/LearnOpenTK):
GL.ClearColor(c);
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
GL.LoadIdentity();

        _shader.Use();

        GL.BindVertexArray(_vertexArrayObject);

        
        GL.DrawArrays(PrimitiveType.Triangles, 0, 3);

this will cause rendering area less than true window size.(less width with 90pix,less height with 20pix...).But delete GL.Enable(EnableCap.ScissorTest); have no rendering area problem.
here is my environment.
Windows 10
WPF .net core 3.1 App
OpenTK 4.7.1
GLWpfContrl 4.1.0

Flickering occurs in the Example program.

This is my environment ↓

Black flicker, After that nothing is displayed...

At first the graphics appear fine, but while resizing the window by dragging, there is a black flicker, After that it turns black and nothing appears.
(I have not rewritten anything in the program.)

My image is that the buffer is running out of write space.

As long as you have time, I would appreciate your investigation.
Thank you.

I know there is a SwapBuffers() function in GLControl, is there also SwapBuffers() function in your control? and how should we use it?
thanks.

I tested out the wpf control and it works great locally. I tried remoting in to my work computer with remote desktop and when I run it the window is blank white. It doesn't crash but you can't see anything. Both computers have Windows 10 and nvidia graphics cards with the latest drivers. Also remote desktop worked fine on the old winforms gl control.

Hello, I created a new WPF application for testing and am following the Getting Started instructions in the Readme, but am encountering an issue trying to include GLWpfControl in the window.

Adding xmlns:glWpfControl="clr-namespace:OpenTK.Wpf;assembly=GLWpfControl" to my MainWindow immediately causes error XLS0418 in MainWindow.xaml, i.e. that the assembly "GLWpfControl" could not be found. Additionally, trying to build and run the project regardless then causes error CS0234 to appear from auto-generated code in MainWindow.g.i.cs, i.e. that the type or namespace name "Wpf" couldn't be found in the namespace "OpenTK".

And indeed, IntelliSense offers me all the usual OpenTK namespaces (Audio, Compute, Core, etc.) if I type "OpenTK.[...]" ex. in the window's constructor, but no "Wpf".

I'm using Visual Studio Community 2022 on Windows 10 Pro 21H2, my test project is targeting .NET 6.0, OpenTK and GLWpfControl are the latest stable versions on NuGet (4.7.4 and 4.2.0, respectively).

I'm rather new to WPF, having stuck with WinForms for the longest time, so this might very well be user error. In that case, am I missing something obvious? Is there something else I have to do to reference the assembly correctly, after installing the package? Is the package incompatible with .NET 6.0 and/or VS 2022?

Any help would be very much appreciated.

During some prototyping work, I wanted to compare the performance of GLWpfControl with my current approach for rendering OpenGL content in WPF. I would basically like to measure which approach has the biggest performance overhead. My intent is to open a large window, and compare framerates for both approaches. I don't want to add too much actual content so that the performance overhead is more prominent, so I'm painting a fairly lightweight scene using OpenGL.

This means that I end up with high framerates, even for fairly large windows (3840x1080 in my case, I can't seem to go beyond this size). To get proper FPS results, I disabled Vertical Sync in the NVidia control panel. This has the following effect:

• In the old approach, the framerate is not capped to 60 FPS anymore, and I get framerates of ~250
• Using GLWpfControl, the framerate remains capped at 60 FPS.

The second point is a bit unexpected for me since I didn't see anything in the GLWpfControl source code that indicates a fixed framerate. I might be wrong though.

Is this a bug ?
Is this a normal side-effect of the DirectX-OpenGL interop in GLWpfControl ?
Is the framerate capping something I can enable or disable some other way ?

Note that I'm using OpenTK.GLWpfControl version 3.3.0 since I'm using .Net Framework.

I downloaded GLWpfControl-master tutorial from the OpenTK repository, unfortunately, the project can not execute and it is giving me the following error below, I am using Visual Studio 2022 community version. I want to know whether the problem is unique to my machine or there is something I am not doing correctly.

A project with an Output type of Class Library cannot be started directly. In order to debug this project, add an executable project to this solution which is references the library project. Set the executable project as the startup project.

does this support Quickfont Library? I tried to implement QuickFont but it rendered nothing :(...
a quick repocode for this:
repo

There's currently no way to get the IGraphicsContext that gets created from the control.

I realize there's the ability to pass a custom context via GLWpfControlSettings.ContextToUse, however it would be nice to be able to get the shared one created automatically without having to do it manually.

Here is just a place for me to list a few things that I'm going to hopefully fix up with GLWpfControl:

• VSyncing - Should have the ability to turn on and off just like with GLFW backend for OpenTK.
• Events should be handed for (hopefully) both the control and real time updating.
• It seems as though the example project has a stack overflow exception when pressing any key on my machine.

If anyone has any issues they'd like to add to the list just chuck in a comment and that way we can sort them out by priority and get them fixed up.

Googling the above error gives me a bunch of Minecraft discussions, so I'm at a loss what I'm doing wrong. I have a large 64-bit Win Forms app, .NET 5, I've converted from DirectX 9 to OpenTK 4.4. I have I get the above error at glControl.Start() when I call this method on a class that inherits from ElementHost. I can run the Example project in this repository fine. I even ran the Example project using ES30, OpenTK 4_4, 64 bit, .NET 5 just fine. I'm unable to use a debugging callback because it wants me to load the bindings or a window first and loading the bindings gives me an error as well. I'm calling this Start() method in the main form's Load event, but I tried calling it from the main form's constructor as well (which is created from Main()).

    public bool Start()
    {
        glControl = new GLWpfControl();
        this.Child = glControl;

        //openGLDebugDelegate = new DebugProc(openGLDebugCallback);
        //GL.DebugMessageCallback(openGLDebugDelegate, IntPtr.Zero);
        var settings = new GLWpfControlSettings();
        settings.MajorVersion = 3;
        settings.MinorVersion = 0;
        //settings.GraphicsProfile = ContextProfile.Any;
        glControl.Start(settings);

        RenderContext = new RenderContextGL(this);
        return true;
    }

i tested mouse events(down, up) and test for keyboard events.

mouse events are works great but key events is not triggering.

i want keyboard event firing at only got focused wpfglcontrol.

i already read issue #31 and i think it is not resolved currently.

is this bug or something?

any solution?

best regards.

The links to the examples in the README file are dead. Seems like a leftover from a repository ownership transfer, perhaps? Pretty quick fix, I'll be sending the PR soon, opening an issue for tracking reasons.

Code like this wouldn't work. How can I use GL.Begin(PrimitiveType.Triangles); to draw a triangle?

Hi,

I am having issues with GPU usage where a simple test app is using 20% to 30% GPU while idle and without calling the Clear() method or even rendering anything on the screen.

The GPU usage starts at around 4% and within a few seconds it jump to like 15% and if I hit ALT + Enter to switch to full screen mode it climbs to 30% + which is a hell of a lot of usage for a blank screen. I don't have any issues with any other apps on my machine so I am very confidant it's related to GLWpfControl.

My machine specs:
Windows 10

Test app GPU usage in task manager:

Sample test app:

https://easyupload.io/jifxac
Sorry but Girhub wouldn't let me upload a zip file so I hosted it somewhere else.

Thanks in advance.

It is not shown in Windows Remote Desktop.
I only see a gray screen.
So, looking for a solution, I found the following solution:
#42
By the way, we still use the .Net Framework.
So, I would appreciate it if you could add and release it.

Testing if webhooks works, ignore this issue.

Hi, can we expect the new release with stencil support? As I can see, the code is already there, but it was committed after the latest official 4.1.0. Thanks!

Thansk for a great control!
When I want to dispose GL resources, like textures or frame buffers when the control is no longer used, I found only the Unloaded event provided by WPF. But this event is not called on application shutdown (https://docs.microsoft.com/en-us/dotnet/api/system.windows.frameworkelement.unloaded?view=net-5.0).
I opted for Dispatcher.ShutdownStarted but this will only be called on application shutdown and not on other visual changes, which may require disposal and recreation of resources. Of course I could handle both, but this seems hackish to me.

What is your best practice in this case?

One suggestion in the thread
https://stackoverflow.com/questions/1550212/proper-cleanup-of-wpf-user-controls is to override the OnVisualParentChanged.

I'm developing a windows application using WinUI3 and .Net5.0. Unable to use this control. Are there any alternatives available or should link any WPF related dlls?

Hi team, default sample in the repos works well, but it' on high framerate which is 60. When I render lot's of objects in the control , flickering occured, i think the source the problem maybee d3dimage . I've grope for solution to prevent flicker on d3dimage but failed. Can anyone help me?

Hi,

I have OpenTK 4.7.4 and OpenTK.GLWpfControl 4.2.2, installed from NuGet of Visual Studio 2022.
.net framework version 6.0

After put GLWpfControl into the window, the window keep blank and no response.
if remove the "OpenTkControl.Start" call, the window can show up, with text on the control:
"OpenGL content. Call Start() on the control to begin rendering."

what's the problem? do I need to install something else to make it to work?

<Grid> <GroupBox Header="{Loc Rendered}"> <glWpfControl:GLWpfControl x:Name="OpenTkControl"/> </GroupBox> </Grid>

code:
`
public ThreeDWindow()
{
InitializeComponent();

        var settings = new GLWpfControlSettings
        {
            MajorVersion = 4,
            MinorVersion = 2
        };
        OpenTkControl.Start(settings);

        //GL.Enable(EnableCap.Blend);
        //GL.Enable(EnableCap.DepthTest);
        //GL.Enable(EnableCap.ScissorTest);
    }`

Hi,

Thanks a lot for the library. Would it be possible to make this package compatible with the latest OpenTK version (v4.6.7 as time of writting).

Current dependency is setup as OpenTK (>= 4.3.0 && <4.4.0), I guess making it OpenTK (>= 4.3.0) would fix that.

Thanks a lot!

Hi, I am using this control to ply a video file, and as such need the aspect ratio to stay the same when the window / usercontrol is resized. I am struggling to find a solution for this. Would you be able to point me in the right direction?

Thanks1

This issue is a reminder to remove this line of the example

*I'm targeting .net 5, of course, making a WPF app.
*I'm using Visual Studio Community 2019. My computer only has Intel Integrated Graphics for the gpu.

For some reason, as the title says, the control only renders pitch black.
I've tried changing the OpenGL version on GLWpfControlSettings, and also changing the target framework version from 5.0 to core 3.1, but to no avail.

Here's a snippet of my code:
*Note that i'm inheriting GLWpfControl; i tried using the vanilla GLWpfControl but it also didn't render anything.

//Gets called after InitializeComponent in MainWindow.xaml.cs
public void Initialize()
{
    GLWpfControlSettings settings = new GLWpfControlSettings();
    Start(settings);
}

//Render="GLWpfControl_Render" in the xaml file of the custom control.
void GLWpfControl_Render(TimeSpan delta)
{
    //throw new Exception(GL.CheckFramebufferStatus(FramebufferTarget.Framebuffer).ToString());
    // [ returns FramebufferIncompleteMultisample ]

    GL.ClearColor(Color4.White);
    GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

    throw new Exception(GL.GetError().ToString());
    // [ returns InvalidFramebufferOperationExt ]
}

Is there something I'm missing in order to use these events in the control? MouseMove, SizeChanged, and Render work fine.

<glWpfControl:GLWpfControl
x:Name="OpenTkControl"
KeyUp="OpenTkControl_KeyUp"
MouseMove="OpenTkControl_MouseMove"
LostFocus="OpenTkControl_LostFocus"
GotFocus="OpenTkControl_GotFocus"
Loaded="OpenTkControl_Loaded"
SizeChanged="OpenTkControl_Resize"
Render="OpenTkControl_OnRender"
/>

I am using the control with the code from the provided example and I get the following result :

Am I doing something wrong?