C#

by ignoring queued mouse events. i got my answer.

@everybody: thank you every one for your suggestions.

[DllImport("yourdllname.dll")]
public static extern returnType FunctionName(parameterType parameter);

Andy_L_J wrote:

some of the constructs are a little confusing!

public event PropertyChangedEventHandler PropertyChanged;

protected virtual void OnPropertyChanged(string propertyName)
{
  if (this.PropertyChanged != null)
  {
    PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
  }
}

OriginalGriff wrote:

at least there is a clear distinction between a method call and an index!

1. The method signature. There is nothing wrong with what you have, but normally (in non WPF) the EventArgs instance is passed as a parameter:
   
   C#

   protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)

   This is of no consequence as your code will function exactly the same, but I thought I'd mention it.
2. This is more important. There is a potential race condition with your null test. It is possible that PropertyChanged could become null between the check and you calling it. I have seen this too in much WPF code, so maybe there is some internal locking or something going on behind the scenes in WPF. The normal way would be to create a copy and call the copy:
   
   C#

   PropertyChangedEventHandler eh = PropertyChanged;
   if(eh != null)
   {
       eh(...);
   }

   
   

public event PropertyChangedEventHandler PropertyChanged;
 
protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)
{
    PropertyChangedEventHandler eh = PropertyChanged;
    if(eh != null)
        eh(this, e);
}

DaveyM69 wrote:

if(eh != null)
eh(this, e);