public class SupportApplications: object
{
    public string Name { get; set; } = "{Please Set}";
    public ExecutionTime ExecutionTime { get; set; } = ExecutionTime.BeforeLaunch;
    public ExecutionMode ExecutionMode { get; set; } = ExecutionMode.Exclusive;
}

public class ComputerVM : BaseVM
{
    [Editor(typeof(GenericCollectionEditor), typeof(UITypeEditor))]
    public List<SupportApplications> SupportApplications
    { get { return Computer.BigBoxSupportApplications; } set { Computer.BigBoxSupportApplications = value; OnPropertyChanged(); } }
}

internal class GenericCollectionEditor : UITypeEditor
{
    public override UITypeEditorEditStyle GetEditStyle(System.ComponentModel.ITypeDescriptorContext context)
    {
        if (context == null && context.Instance == null) return base.GetEditStyle(context);
        return UITypeEditorEditStyle.Modal;
    }

    public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
    {
        if (context == null || provider == null || context.Instance == null) return value;

        IWindowsFormsEditorService editorService = (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));

        Type type = value.GetType().GetGenericArguments().SingleOrDefault() ?? typeof(object);

        GenericCollectionEditorForm form = new GenericCollectionEditorForm((List<object>)value, type);

        if (editorService.ShowDialog(form) == System.Windows.Forms.DialogResult.OK)
        {
            return form.Objects.ToList();
        }

        return base.EditValue(context, provider, value);
    }
}

public partial class GenericCollectionEditorForm : FormViewBase
{
    public List<object> Objects { get; set; }

    private Type type = null;

    private BindingSource objectsBindingSource = new BindingSource();

    public GenericCollectionEditorForm(List<object> objects, Type type)
    {
        Objects = objects;
        this.type = type;

        objectsBindingSource.DataSource = Objects;
        MainLB.DataSource = objectsBindingSource;
    }

    private void AddBT_Click(object sender, EventArgs e)
    {
        if (type == null) return;
        Objects.Add(type);
        RefreshEffectListDataBindings();
    }

    private void MainLB_SelectedValueChanged(object sender, EventArgs e)
    {
        MainPG.SelectedObject = MainLB.SelectedItem;
    }

    private void RefreshEffectListDataBindings()
    {
        MainLB.DataSource = null;
        MainLB.DataSource = objectsBindingSource;
    }

    private void DeleteBT_Click(object sender, EventArgs e)
    {
        if (MainLB.SelectedItems.Count == 0) return;
        Objects.Remove(objectsBindingSource.Current);
        RefreshEffectListDataBindings();
    }
}