Not sure there is a way to do this without getting your hands dirty with a little actionscript, but fear not! I'm here to help
Create a new movieclip, draw a rectangle the size you want your bar to be. Close the movieclip and position it where you want it to be. Reopen the movieclip and select your triangle, convert it to a movieclip name this movieclip "contents" open this child movie and add your buttons.
Look at attached