WPF: Specific input textboxes (for phone numbers and such)
I don't know what this is called, but I'm sure theres a name for this and it has been done multiple times.

I have some textboxes that ideally would only allow specific input, like a box for phone number, bank account numbers and stuff like that.  
For instance, a phone number input should be in the following format: 000-000-0000  but I'd also like it to accept a number without an area code like : 000-0000  

Now I have made a control derived from textbox that accepts only numeric input, but I have no idea how I would get the dashes to appear in the right spots without doing some fugly hacks in the TextChanged event.

I know this has probably been done to death, I tried to google but I didn't have the right words.

Thanks in advance.
WPF: Specific input textboxes (for phone numbers and such)
===

I don't know what this is called, but I'm sure theres a name for this and it has been done multiple times.

I have some textboxes that ideally would only allow specific input, like a box for phone number, bank account numbers and stuff like that.  
For instance, a phone number input should be in the following format: 000-000-0000  but I'd also like it to accept a number without an area code like : 000-0000  

Now I have made a control derived from textbox that accepts only numeric input, but I have no idea how I would get the dashes to appear in the right spots without doing some fugly hacks in the TextChanged event.

I know this has probably been done to death, I tried to google but I didn't have the right words.

Thanks in advance.