0x00: Blank window (fill with gradient)
0x01: Top-left border corner
0x02: Top border
0x03: Top-right border corner
0x04: Left border
0x05: Right border
0x06: Bottom-left border corner
0x07: Bottom border
0x08: Bottom-right border corner
0x09: Left border corners
0x0A: Top/Bottom borders
0x0B: Right border corners
0x0C: Top border corners
0x0D: Left/Right borders
0x0E: Bottom border corners
0x0F: Top-left border corner (no empty space)
and more...