Hello Mister Pegge,
before you continue, your latest oxygen.dll has a bug.
take a look below at "stray comma.jpg"
include "gdip.inc"
window 640,480,1
hdc = GetBufferDC()
%UnitPixel = 2
%UnitPoint = 3   
Type RectF
   single x 
   single y 
   single w 
   single h 
End Type
Extern Lib "gdiplus.dll"
! GdipCreateFontFamilyFromName 
! GdipDeleteFontFamily
! GdipCreateSolidFill
! GdipDrawString
! GdipCreateFont
! GdipDeleteFont
! GdipDeleteBrush
End Extern
wstring font
Sub SetFontEx(wstring fontname)
    font = fontname
end sub    
Sub DrawString(single x, y, height, wstring txt)
    RECTF fRect = {x, y, ScrW, ScrH}    '<<   here is the wrongdoer             
    sys pFont, pFontFamily, pBrush 
    GdipCreateFontFamilyFromName font, NULL, &pFontFamily
    GdipCreateFont pFontFamily, height, FontStyleRegular, UnitPoint, &pFont
    GdipCreateSolidFill 0xFFFFFFFF, &pBrush
    GdipDrawString hdc, txt, Len(txt), pFont, fRect, NULL, pBrush
    GdipDeleteFont  pFont
    GdipDeleteBrush pBrush
    GdipDeleteFontFamily pFontFamily
End Sub
SetFontEx "david"
DrawString 100,100,24,"Hello GdiPlus World"
SetFontEx "georgia"
DrawString 100,124,24,"Hello GdiPlus World"
SetFontEx "gisha"
DrawString 100,158,24,"Hello GdiPlus World"
SetFontEx "impact"
DrawString 100,186,24,"Hello GdiPlus World"
setfontEx "wingdings"
DrawString 100,300,24,"OOOOOOOOOOOO"
DrawString 100,330,24,"XXXXXXXXXXXXXXX"
for i=0 to 640 step 40
    DrawString i,0x0,24,"a"
    DrawString i,430,24,"b"
next
waitkey
winEnd
.