ExplainThis Highlighting Out-of-Sync with Current Cursor Position in Exercise Mode

[russell-rozenbaum]

The highlighting appears to lag behind cursor actions within exercise mode editors. This, in turn, causes incorrect syntax to be highlighted, given the location of the cursor. The explanations in the sidebar appear correct, however.

Note: This is separate from #1675, and appears in a branch without the merge of #1444

Screen.Recording.2025-06-12.at.12.41.51.PM.mov