In perl/tk icons can't be neither shaped nor transparent (for
image formats that support tranparency). This is not really
a bug more a limitation due to the very old version of Tk
available within perl/tk and the way images are handled in
Tkzinc.

Text stippling is not available under openGL.

Line ends and line joins are not fully implemented under openGL.
The default behavior if to draw round ends and joins.

Line dashes are not really usable in openGL. Some cases work ok,
like aligned rectangles and other not, like curves and arcs.

Tiling/stippling begin on the item or item bounding box edge
rather than on the border edge so that the tile/stipple is
partially masked by the border.

Maps are not rendered filled in openGL. The code of maps still
lags behind.