@jan_klaassen
I totally agree, there is no way of perfect fitting scanlines on non integer stretching. That said for larger resolutions the penalty gets reduced.
Integer overscan offers perfectly fitting scanlines for any resolution but loses some lines. In integer overscan lines lost are reduced as resolution increases.
Finally for non integer stretching there is the MAME solution, thin scanlines. These are not accurate but always perfect fitting (even on badly stretched framebuffers).
@dink
Thank you for caring about this. You can find the latest source attached to this message (it's based on source version 29738). If memory doesn't fail me modified files are:
vid_d3d.cpp
menu.cpp
resource.h
scrn.cpp
cona.cpp
interface.h
vid_interface.cpp
vid_directx_support.cpp
app.rc
app_gnu.rc