Background/foreground rendering strangely for certain unicode characters

[noprobelm]

Describe the bug
Hi, thanks for creating such an awesome tool.

I apologize in advance if this is a user error, but I can't seem to figure it out. When recording a ▄ character in the terminal, the background/foreground render unexpectedly and unpredictably (there seems to be some kind of overlap in the colors where there shouldn't be).

The corresponding .cast playback looks as I would expect it to. Here are some examples:

To Reproduce
Steps to reproduce the behavior:

1. Record a ▄ character in the termianl (ensure the background and foreground are different colors). Convert it to a gif using agg

Expected behavior
No background/foreground overlap should occur

Versions:

• OS: EndeavourOS
• agg 1.4.3

Output with verbose flag:

[INFO  agg] terminal size: 140x35
[INFO  agg] selected font families: ["JetBrains Mono", "Fira Code", "DejaVu Sans Mono", "Liberation Mono", "DejaVu Sans"]
[INFO  agg] selected theme: dracula
[INFO  agg] gif dimensions: 1193x706

[ku1ik]

Could you paste the cast file for the 2nd gif? It would help for me to know what characters and control sequences were recorded in the first place. Thanks.

[noprobelm]

I discarded the old cast file, here's a new one I just recorded. It uses the same character. It's worth noting this will happen with other block element characters as well.

lower_half_block.txt