Re: Down-resolution on dx-nothing
1) Window Layout > Swap Groups tab > Swap Group 1 > Set the Reset Region to NONE
2) Regions tab > Resize Regions 1 & 2 to be 1900x1200 rather than 2560x1600 (doesn't matter if you keep or delete Region 4 at this point)
This will make all of your regions render at the resolution that they're set to in the Regions editor and they will no longer be stretched to fullscreen. Also, if your Windows DPI/Font scaling is set to anything besides 100% your regions may act funny (Control Panel > Display > 100%).