gui.cs | Console-based user interface toolkit for .NET applications | User Interface library

You are using .NET SDK from snap. When you run your app with such SDK, snap will start your program in a sandbox environment (that nobody has asked for, especially for an SDK tool, but it does that anyway) with its own root file system without native dependencies required by Avalonia. Nothing you install on the main system will affect said sandbox. It just won't work.

Purge snap-installed .NET SDK from your system (preferably alongside with snap itself) and install using instructions from https://docs.microsoft.com/en-us/dotnet/core/install/linux-ubuntu#2004- :

I found a similar issue reported on the highcharts-angular repository.

https://github.com/highcharts/highcharts-angular/issues/259#issuecomment-762787358

It looks like the Fullscreen module requires the Exporting module so to fix the problem you could try importing & initializing the Exporting module.

This change does not display the error but the event seems not to be firing.

As soon as I want to add another one, the rendering shows weird behavior

Of course, because the indices for the 2nd and following objects are wrong. You need to add the sum of the vertices of the previous meshes to the indexes. To the indices of the first mesh you have to add 0, to the indices of the 2nd mesh you have to add the number of vertices of the 1st mesh, to the indices of the 3rd mesh you have to add the sum of the vertices of the 1st and 2nd mesh, ...

Of course, it doesn't need to be too complicated - refactor your update to just take in a listview parameter:

The Threading part is not an issue here. You just need to handle the Form creation in a slightly different way:

First setup:

• The Form's Handle creation can be forced calling CreateHandle() right after InitializeComponent() (the .Net Source code related to the method call is more interesting, also note the call to UpdateHandleWithOwner()).
• The next condition to show the output of the worker thread, is that the Form is also Visible, since also the TextBox Handle needs to exist when it's invoked.
• The Gui class needs to BeginInvoke() the Form's AddLine() method, since the method call is generated in a different thread (the Gui object is used by the Worker object thread).
• I've added a public property to the Gui class: public bool CanWrite: the Worker class can inspect this property to determine where it should write its output.
  The public property returns: dialogForm != null && dialogForm.Visible;, this because ↓:
• DialogForm is shown calling ShowDialog(): this implies that when the DialogForm is closed, the Form is not disposed. Also, the object still has a reference in the Gui class. When it's closed, its Visible property returns false.

Second setup:

• Since (based on comments) this Console application should output to the DialogForm Form when a Gui object is created and the Dialog is not necessarily shown immediately, the TextBox Control in DialogForm should cache lines of text posted by the Thread in the Worker class.
  This requires a simple edit: change dialogForm != null && dialogForm.IsVisible in just dialogForm != null, then verify the handle status before Gui.AddLine() is called and caching lines of text if the handle is not available at this time.
• The Owner Form, MainForm, instructs DialogForm to recreate its handle when DialogForm.ShowDialog() returns. Since ShowDialog() is used to show DialogForm, the form is not disposed. Recreating the handle doesn't casuse child controls to lose their content.

Implement both option:

The IsVisible property check could become a Property of Gui, something like bool UpdateOnDialogVisible, to test on CanWrite, so the text will be written to the TextBox depending on the status of this property.

_{Tested in:}

<sub>- Windows 7 (I don't have a WinXP machine available)
- .Net Framework 4.0
- C# 5</sub>

In Program.cs: