I was recently working with GDI+ drawing when I found the need to modify a Pen's Width property. I often use the Pens class as a matter of convenience so my first thought was to simply write the following:
Pens.Yellow.Width = 3;
However, that did not work too well as I was greeted with the exception "You may not change this Pen because it does not belong to you." When I read the message I immediately realized that I had made a mistake, but the wording of the exception message also made me laugh a little. It sounds like the Drawing namespace is a little kid that doesn't want me to play with its toys, although in that case it would probably just say "Mine!"
In case you are wondering, the Pens class houses a number of static properties representing a number of colors, including Yellow. The static Yellow property will create a new immutable Pen object with width 1 when you first use it and then store it in a hash table for future use. Future calls to Pens.Yellow will get the same Pen object that was previously stored in the hash table. This is done because GDI Pens are a limited resource that needs to be conserved.
