Comments by Richard Deeming (Top 200 by date)

this.Resources.BeginInit();
try
{
    this.Resources.MergedDictionaries.Clear();
    this.Resources.MergedDictionaries.Add(resX);
}
finally
{
    this.Resources.EndInit();
}

if (!uniqueComp.TryGetValue(cmp1[i].name, out List<object> list))
{
    list = new List<object>();
    uniqueComp.Add(cmp1[i].name, list);
}

list.Add(...);

const string sql = @"SELECT Invoices.* 
FROM Invoices 
INNER JOIN Customers ON Invoices.custID = Customers.custID 
WHERE Invoices.custID Like @custID 
And Invoices.Series = N'ΑΛΕ'";

using (SqlConnection con = new SqlConnection(...))
using (SqlCommand cmd = new SqlCommand(sql, con))
{
    cmd.Parameters.AddWithValue("@custID", custID.Text);
    
    con.Open();
    using (SqlDataReader rdr = cmd.ExecuteReader())
    {
        ...
    }
}

public class Level1
{
    private readonly TaskCompletionSource<bool> _result = new TaskCompletionSource<bool>();
    
    private void OnReceive(IAsyncResult asyn)
    {
	    ...code that receives data
        _result.TrySetResult(true);
    }
    
    public Task<bool> Result => _result.Task;
}

lvl1 = new Level1();
log.Info($"[{symbol}] Level 1 initialized.");
lvl1.Request(symbol);
bool result = await lvl1.Result;
log.Info($"Level 1 result 1 is {result}");

IEnumerable<int> duplicateKeys = counts1
    .GroupBy(x => x.Value, new ArrayEqualityComparer<double>())
    .Where(x => x.Count() > 1)
    .SelectMany(g => g).Select(i => i.Key);

List<int> keysToRemove = counts1.Keys.Except(duplicateKeys).ToList();

foreach (int key in keysToRemove)
{
    counts1.Remove(key);
}

public class DoubleEqualityComparer : IEqualityComparer<double>
{
    private readonly double _epsilon;
    
    public DoubleEqualityComparer(double epsilon)
    {
        if (double.IsNaN(epsilon) || double.IsInfinity(epsilon)) throw new ArgumentOutOfRangeException();
        _epsilon = Math.Abs(epsilon);
    }
    
    public DoubleEqualityComparer()
    {
        _epsilon = double.Epsilon;
    }
    
    public int GetHashCode(double obj) => 0; // See note
    public bool Equals(double x, double y) => Math.Abs(x - y) <= _epsilon;
}

var duplicateValues = counts1.GroupBy(x => x.Value, new ArrayEqualityComparer<double>(new DoubleComparer(1E-12))).Where(x => x.Count() > 1);

<Series Name="Default" CustomProperties="PieLabelStyle = Outside" Label="Very very long label (#VAL)"></Series>