Question: I have an application that supports several different combinations of viewable items. each view can be toggled on and of by clicking on its corresponding tree node. The problem is that I do not want to store each individual node.checked boolean in a seperate boolean in my .settings file.

So I am currently attempting to use a bit mask, however I do not know how to add that type to the selectable types of the settings file Editor.

What should I do to make that a selectable type for saving?

Answer: 
An enum type is an Int32 behind the scenes - in fact variables of enum types can be assigned any integer values, even if those values are not in the original enum. If you used an integer type in the setting, you could cast it to your defined enum type to use it. There is no checking that the integer value is defined by the enum.

Be careful using a bitmask for this in a settings file though as it might get difficult to work out the value for the setting. If you wanted bits 1 and 3 set to true, for example, the value you would have to put in the settings file would be "5", since this is the integer that has the first and third bits set to 1.

In code you can use the bitshift operator `<<` to make reading the value easier, or `Enum.HasFlag` (<http://msdn.microsoft.com/en-us/library/system.enum.hasflag.aspx>) in .NET 4 and above.
You can use just `Int32` type. Bitmasks are sets of nonzero bits in a integer number (4 bytes) or other specified integer type (e.g. `Int16`)