Added menu structure.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
Added common menu bar for mac.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>
Don't exit when the last frame is deleted on Mac.

Signed-off-by: Kristian Duske <kristian.duske@gmail.com>