I have updated the BBCSDL library gfxlib.bbc to version 1.4. This includes three new functions, extending its (partial) compatibility with David Williams's GFXLIB2 library for BB4W:
PROC_gfxPlotScaleAlphaBlend (similar to GFXLIB_PlotAlphaBlend)
PROC_gfxPlotScaleDissolve (similar to GFXLIB_PlotDissolve2)
PROC_gfxInvert (similar to GFXLIB_RectangleXOR when XORing with &FFFFFF)
The new version may be downloaded from GitHub here.