[Toni Wilen]

Actually 800x300 Super72 is not scandoubled. It really has only 300 lines. It is the monitor that adjusts to this mode and "scales" it to fill whole screen (using vsync and hsync lengths as usual)

Real scandoubled modes draw same scanline twice. (for example DBLPAL and DBLNTSC)

Problem is that emulation detects this mode as scandoubled = emulation doubling is disabled because doublescanning doubles it back to original size. (or real doublescanned modes would get doubled twice)

Detecting scandoubling using hardware parameters only is impossible for all conditions, unless there are some hardwired parameters for known common modes.

VTOTAL alone can't be used for detecting anything. (How are you going to know if for example vtotal=600 is 300 doublescanned lines or 600 "real" lines?).

EDIT: but I guess if mode is detected as doublescanned and VTOTAL is "too small", it probably isn't doublescanned after all.