upgrade to .net6 part 1

Pilz.Drawing.Drawing3D.OpenGLRenderer/Preview/ModelPreview.vb

@@ -6,10 +6,11 @@ Imports OpenTK
 Imports OpenTK.Graphics.OpenGL
 Imports Pilz.S3DFileParser
 Imports Point = System.Drawing.Point
-Imports KeyboardState = OpenTK.Input.KeyboardState
-Imports Keyboard = OpenTK.Input.Keyboard
-Imports Key = OpenTK.Input.Key
 Imports Color = System.Drawing.Color
+Imports OpenTK.Mathematics
+Imports OpenTK.WinForms
+Imports OpenTK.Input
+Imports OpenTK.Windowing.GraphicsLibraryFramework
 
 Namespace PreviewN
 
@@ -132,7 +133,6 @@ Namespace PreviewN
             Me.glControl1.Size = Me.ClientSize
             Me.glControl1.TabIndex = 0
             Me.glControl1.TabStop = False
-            Me.glControl1.VSync = False
             Me.Controls.Add(Me.glControl1)
             Me.ResumeLayout(False)
 
@@ -247,7 +247,7 @@ Namespace PreviewN
         End Sub
 
         Private Sub glControl1_Resize(sender As Object, e As EventArgs) Handles glControl1.Resize
-            glControl1.Context.Update(glControl1.WindowInfo)
+            'glControl1.Context.Update(glControl1.WindowInfo)
             GL.Viewport(0, 0, glControl1.Width, glControl1.Height)
             ProjMatrix = Matrix4.CreatePerspectiveFieldOfView(FOV, glControl1.Width / glControl1.Height, 100.0F, 100000.0F)
             glControl1.Invalidate()