Problem with Java App running on OS X

Hello Everyone,
I am relatively new to Java and this website. I am working towards creating a 2D RPG game. I found a game engine from tutorials on Youtube. The game engine and it’s sample RPG and the mapmaker the programmer created run fine on my Windows 7 Desktop computer. The problem is with it running on my MacBook Air. When I run the app, a window opens with the app name in the title bar but the window is blank (just the standard gray background). The console shows the game running but it seems to not be displaying the title screen. I should say the mapmaker app runs the same way. So I’m thinking it has something to with OS X. Can anyone give me some pointers as to where to look or what to look for?

Thank you in advance!
Mark