Defects in color theme and Unicode characters when deleting text

[GregorPercic]

When I delete some text in between reloading an .agda file, these two bugs occur:

1. the color theme becomes inconsistent (and nonsensical),
2. some Unicode characters (from experience, always those high up in the coding table, such as 𝕍, 𝒫, etc.) turn into gibberish, such as ��.

Reloading fixes both issues. My suspicion is that characters "high up" in the table cause a one-character shift due to having a longer encoding, which the program for the color theme and display of Unicode characters does not take into account.

An example in pictures (normal vs. these two bugs present):

The source code from the above example is in this repository. I think both bugs can be replicated simply by deleting {_} character by character.