Friday, April 22, 2005

Annoying .NET SP1 GroupBox and FlatStyle.System bug

I encountered this nasty .NET 1.1 SP1 bug in the Windows.Forms groupbox control yesterday, and unfortunately the workaround is not that straightforward to implement in reality.

My own less-than-perfect workaround is instead to disable FlatStyle on nested groupboxes. Here's the method I use to apply the styles:

  #region SetObjectPropertyValue
  /// <summary>
  /// Attempts to set the value of a property of an object.
  /// Returns true if successful, false if not.
  /// </summary>
  /// <param name="objectInstance">The instance of the object</param>
  /// <param name="propertyName">The name of the property</param>
  /// <param name="propertyValue">The desired value of the property</param>
  /// <returns>True if successful, false if not.</returns>
  public static bool SetObjectPropertyValue(object objectInstance, string propertyName, object propertyValue)
   bool isSet = false;
    //use reflection to attempt to set the FlatStyle of controls
    Type controlType = objectInstance.GetType();
    //attempt to get the Control's specified property
    PropertyInfo prop = controlType.GetProperty(propertyName);
    //if it exists and is settable, set it
    if (prop != null && prop.CanWrite)
     prop.SetValue(objectInstance, propertyValue, null);
     isSet = true;
   catch {}
   return isSet;
  #endregion (SetObjectPropertyValue)

  #region SetFlatStyleSystem
  /// <summary>
  /// Method used recursively to set the FlatStyle property to system 
  /// for all descendants of a control.  Called from the form's constructor.
  /// </summary>
  /// <remarks>
  /// Originally copied from Chris Sells' Windows Forms Programming in C#, 
  /// then embellished by Oskar Austegard (added Reflection).
  /// Requires that the main form's Main() method includes the line
  /// <code>Application.EnableVisualStyles();</code>
  /// prior to showing any UI.
  /// </remarks>
  /// <param name="parent">Control to start with</param>
  public static void SetFlatStyleSystem(Control parent)
   //loop through any & all child controls
   foreach(Control control in parent.Controls)
    //don't do this for labels (changes their vertical alignment)
    //and for groupboxes contained within other groupboxes (which due to a bug render with a large font)
    if (!(control is Label || (control is GroupBox && control.Parent is GroupBox)))
     SetObjectPropertyValue(control, "FlatStyle", FlatStyle.System);
    //Set contained controls' FlatStyle as well


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