draw_glyph
Description:
Draws a single glyph with coordinates in device space.
Parameters:
| this | a `PangoRenderer` | 
| font | a `PangoFont` | 
| glyph | the glyph index of a single glyph | 
| x | X coordinate of left edge of baseline of glyph | 
| y | Y coordinate of left edge of baseline of glyph |