Hello Tormod,

while looking at the code again, I start getting some evidence that the "+7" offset addition really is related to panels with a horizontal hardware resolution of 1400 pixels. I ran doxygen over some old versions of the savage driver to dig into the history and possible changes to the worse.
Namely I took version 1.1.26 and 1.1.27. The interesting version is 1.1.26, which has a rather different structure in the expansion code (but the same main bug not to scale the lower right corner of the drawing area).

Here the addition of +7 to the offset is handled completely conditional. At a first glance, it seems to be dependent on two values, the panel width and the selected scaling factors. At a second look, I start getting the opinion that it is only related to the width as it is likely that certain scaling factors are exclusive to this display width.

Whenever the width of the display is checked within a scaling factor condition, the +7 only gets added when the width equals 1400.

Here is the code - in one case even the Y offset is corrected when a 1400 pixel display is present.

01879     switch( XFactor )
01880     {
01881         case 1:
01882             psav->XExpansion = 0x00010001;
01883             psav->displayXoffset = 
01884                 (((PanelSizeX - ViewPortWidth) / 2) + 0x7) & 0xFFF8;
01885             break;
01886 
01887         case 3:
01888             psav->XExpansion = 0x00090008;
01889             psav->displayXoffset = 
01890                 (((PanelSizeX - ((9 * ViewPortWidth)/8)) / 2) + 0x7) & 0xFFF8;
01891             break;
01892 
01893         case 4:
01894             psav->XExpansion = 0x00050004;
01895 
01896             if ((psav->cxScreen == 800) && (PanelSizeX !=1400))
01897             {
01898                 psav->displayXoffset = 
01899                     (((PanelSizeX - ((5 * ViewPortWidth)/4)) / 2) ) & 0xFFF8; 
01900             }
01901             else
01902             {
01903                 psav->displayXoffset = 
01904                     (((PanelSizeX - ((5 * ViewPortWidth)/4)) / 2) +0x7) & 0xFFF8;
01905             }
01906             break;
01907 
01908         case 6:
01909             psav->XExpansion = 0x00030002;
01910             psav->displayXoffset = 
01911                 (((PanelSizeX - ((3 * ViewPortWidth)/2)) / 2) + 0x7) & 0xFFF8;
01912             break;
01913 
01914         case 7:
01915             psav->XExpansion = 0x00020001;
01916             psav->displayXoffset = 
01917                 (((PanelSizeX - (2 * ViewPortWidth)) / 2) + 0x7) & 0xFFF8;
01918             break;
01919     }
01920         
01921     switch( YFactor )
01922     {
01923         case 0:
01924             psav->YExpansion = 0x00010001;
01925             psav->displayYoffset = (PanelSizeY - ViewPortHeight) / 2;
01926             break;
01927         case 1:
01928             psav->YExpansion = 0x00010001;
01929             psav->displayYoffset = (PanelSizeY - ViewPortHeight) / 2;
01930             break;
01931         case 2:
01932             psav->YExpansion = 0x00040003;
01933             psav->displayYoffset = (PanelSizeY - ((4 * ViewPortHeight)/3)) / 2;
01934             break;
01935         case 4:
01936             psav->YExpansion = 0x00050004;
01937             psav->displayYoffset = (PanelSizeY - ((5 * ViewPortHeight)/4)) / 2;
01938             break;
01939         case 5:
01940             psav->YExpansion = 0x00040003;
01941 
01942             if((psav->cxScreen == 1024)&&(PanelSizeX ==1400))
01943             {
01944                 psav->displayYoffset = 
01945                     ((PanelSizeY - ((4 * ViewPortHeight)/3)) / 2) - 0x1 ;
01946             }
01947             else
01948             {
01949                 psav->displayYoffset = (PanelSizeY - ((4 * ViewPortHeight)/3)) / 2;
01950             }
01951             break;