Here is a couple tweaks to key functionality within the code editor that I think would be an improvement, and bring GMS2 closer to a more standardized code editor.
While holding shift to select text, the following keys traverse text as they normally would: shift + { left, right, up, down...
It's kind of strange that statements like "a[i ][j] = b[i ][j]" aren't allowed in GML. It's not something I've ever seen in any other language, and it doesn't really make sense.
Indexing is basically a function that takes whatever's in front of it and reduces its dimension by one, something...
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I also provide artwork, programming and sound effects.
If you want I can expand my marketplace with any requests...