Hi there!
I'm not sure if I understand, sorry I'm tired and english is not my native language.
1) Are you saying that the bitmap font works everywhere, but not on the title screen window when using the Casper Gaming plugin?
2) And, when you say does not work, you mean the window just not show any letter?
3) Did you are using the latest versions from bitmap font(2.4.2) and from the casper plugin?