The BackColor property does not support transparent colors unless the SupportsTransparentBackColor value of System.Windows.Forms..::.ControlStyles is set to true.
The BackColor property is an ambient property. An ambient property is a control property that, if not set, is retrieved from the parent control. For example, a Button will have the same BackColor as its parent Form by default. For more information about ambient properties, see the AmbientProperties class or the Control class overview.
Notes to Inheritors: When overriding the BackColor property in a derived class, use the base class's BackColor property to extend the base implementation. Otherwise, you must provide all the implementation. You are not required to override both the get and set accessors of the BackColor property; you can override only one if needed.
Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note:
Setting the background color to transparent is not supported on the .NET Compact Framework. For labels, use the DrawString method instead of a label control to achieve a similar effect.