Root cause of the broken MFD2 display: CMFD_Device::BeginScene() cleared
the right device back buffer at old sh_step==0, but with the stagger the
right device flip also fired in that same frame (new sh_step==1 = old
sh_step==0 after increment). The flip presented a just-cleared buffer
with only the grid, no channel data.
Fix: split BeginScene for mode 4 - left device (step 0) vs right device
(step 1). Add BeginSceneRight() called from WinMain at old sh_step==1.
The right device flip at new sh_step==1 (= old sh_step==0) now shows
channels 3-4 rendered at steps 5-6 of the previous cycle - correct.
Cycle for mode 4 with stagger:
old sh_step 0: radar+left BeginScene, no flip
new sh_step 1: flip right MFD (shows prev cycle channels 3-4)
old sh_step 1: right BeginScene (clear+grid)
old sh_step 2-4: channels 0-2 -> left device
old sh_step 5-6: channels 3-4 -> right device
new sh_step 0: flip radar+left MFD (shows prev cycle channels 0-2)
dicion
eaa5fd3bbe