The button, though if sections are missing, try resizing the window. If the comment window is not receiving focus, click on the upper left corner.
Comments are text associated with individual moves. You can add comments by typing them in the entry box (where the Control-A, Control-Z and Control-Y shortcuts can be used to manipulate text and undo changes). Comments are automatically stored whenever you move to another position in the game, or move the mouse away from the Comment Editor.
Comments may also exist at the start of a game or variation. To add a comment prefixing a variation go to the variation's first move; then move back one move before entering the comment.
With the focus in the Comment Editor, one can move the game forward and back by pressing the control+left/right keys. Control-Enter saves the comment and closes the window.
Scid uses the PGN Standard and NAGs for annotation symbols. While the most common symbols are displayed as Ascii characters (such as "!" or "+-"), others must be entered as the appropriate numeric value (ie - a number from 1 to 255). For example, the NAG value 36 means "White has the initiative" and will be displayed as "$36" in the PGN window.
The most common move evaluation symbols (!, ?, !!, ??, !? and ?!) can be added firectly from the main window by typing the symbol followed by the [Return] key. This is especially useful if you are entering chess moves using the keyboard.
In addition to text comments, Scid can also draw colour symbols and arrows on the board.
These can be drawn straight onto the main board, or more detailed drawings can be made
in the Comment Editor by pressing to show/hide a small board and diagrams.
Arrows can be drawn in two ways - In the Main Board, hold Control then click on the start square and then end square. Or in the Comment Editor, arrows can be drawn (and erased) by dragging between two squares. The arrow width and length can be altered in the Comment Editor.
Similarly, hold Shift and click on the main board to colour a square, or click on any square in the Comment Editor board to add the selected colour/mark.
The comments associated with these diagrams are visible as special % codes in the PGN window, but can be hidden by selecting "Hide Square/Arrow Codes" in the PGN window Options.