startstuff there are TWO ways to change to fullscreen mode
1 start entrenchment, click on options then click on video, you will then see the use window tickbox remove the tick & click on apply
2 locate your user.setting file in the setting folder next toy your mods folders, edit line 13 which reads 'VideoIsWindowed TRUE' to read 'VideoIsWindowed FALSE', save and then start entrenchment or sins
hope this helps
harpo