Thank you for the reported problem.
As you have found out, the multi-monitor setup works fine when using hardware rendering but when using software rendering the 3D scene does not redraw correctly (the D3DImage that is used to send the rendered 3D scene to WPF is not refreshed).
Waking up from sleep or changing the primary monitor should be handled by Windows, but also when using hardware rendering there are some cases when this is not done correctly without some additional "intervention" from DXEngine. It seems that some additional code will be needed to specially handle the case when using software rendering (hopefully it is possible to fix that, though the WPF's error UCEERR_RENDERTHREADFAILURE does not look good).
I am finishing the preparation for the next release of Ab3d.PowerToys and Ab3d.DXEngine. Anyway I will try to find the cause of this problem and include the fix into this release.+
As you have found out, the multi-monitor setup works fine when using hardware rendering but when using software rendering the 3D scene does not redraw correctly (the D3DImage that is used to send the rendered 3D scene to WPF is not refreshed).
Waking up from sleep or changing the primary monitor should be handled by Windows, but also when using hardware rendering there are some cases when this is not done correctly without some additional "intervention" from DXEngine. It seems that some additional code will be needed to specially handle the case when using software rendering (hopefully it is possible to fix that, though the WPF's error UCEERR_RENDERTHREADFAILURE does not look good).
I am finishing the preparation for the next release of Ab3d.PowerToys and Ab3d.DXEngine. Anyway I will try to find the cause of this problem and include the fix into this release.+
Andrej Benedik