SSMS 18.4 crashes (and usually restarts) when ALT-selecting code point U+0090 in query editor, but only in block comment
When Unicode code point U+0090 (non-printable character: Device Control String) is in a block comment (inline comments are fine), attempting to highlight the character by pressing the
ALT key while holding down the left mouse button will cause SSMS 18.4 to freeze for a few seconds and then crash (and often, but not always, restart). This happens in the Query Editor, and does not require being connected to a database.
To reproduce, copy and paste the T-SQL below into the query editor. The T-SQL already contains U+0090, but if that doesn't come through, then just execute the commented-out
SELECT statement, select the cell from the result grid, and paste into the block comment area. Then, hold down the
ALT key and try selecting the block comment. You might need to go back-and-forth over the block comment a few times as it doesn't always crash on the first pass.
-- SELECT NCHAR(0x90);