Edit
General-purpose dialog for editing text (like trigger/alias match/send text). This is used for single-line input. -> This button is visible if you are editing a regular expression. It invokes a menu of helpful regular expression "insertions" that you can choose. For example, if you want to match on a letter you can click on this button, then choose Character Class -> Letter, and the appropriate regular expression will be inserted at the cursor position. Also, the final entry "Help..." in the menu invokes the Regular Expression help page. (Help topic: dialog=IDD_EDIT) Documentation contents page