Make the still 1920x1080 for BD and 1050x576 for DVD.
I created a still with size 1920 x 1080 and the effect was much as above - it looked OK within the Movie Menu preview but when I ran Preview Disc the black bars were there again.
I have not got as far as actually burning the Blu Ray yet so maybe that would be OK - and even with black bars its not a disaster.
Make an iso and see what it looks like.
Here are the results of today's tests (the finished video is now 12:30 minutes long).
1) Blu-Ray: created a 1.9 GB ISO file. Burnt to Blu-Ray disc via ImgBurn.
When played back on PC there were narrow black horizontal bars at top & bottom of screen when looking @ the menus but video itself had no margins.
When played back on a Blu-Ray player attached to a TV there was a black margin around the entire menus but again the video itself had no margins.
TBH these black margins are not really a big issue.
When played back on both PC & player/TV the audio (music) I had attached to the main menue & scenes menu played until a menue item was selected.
Video quality was good.
2) DVD: created a 732 MB ISO file (no changes made to the project after (1) above). Burnt to DVD disc via ImgBurn.
When played back on PC there were no margins when looking @ the menus & the video itself is OK.
When played back on a DVD player attached to a TV there were also no margins.
In both cases the audio (music) I had attached to the main menue & scenes menu did NOT play at all!
I found the video quality to be rather dissapointing (Export & Share only offered SD 576 as best AFAIK). Can one do anything here?
3) MP4: created a 1.3 GB file. Plays back fine on a PC.